JP2008160308A - COMMUNICATION SYSTEM, VoIP COMMUNICATION EQUIPMENT AND COMMUNICATION METHOD - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system optimum for both quality priority and economicity and rational for a user, capable of securing speech quality by executing end-to-end systematic control between both the VoIP communication equipment of call origination and termination and switching speech communication to a PSTN suppressed in quality degradation when the speech quality is degraded in an IP phone utilizing an IP network, charging for a phone call through the PSTN as well in the VoIP communication equipment on the IP call origination side at all times, and returning from the speech communication through the PSTN to the IP speech communication again when the communication quality of the IP network is improved further, the VoIP communication equipment and a communication method. <P>SOLUTION: IP frames including information capable of control are transmitted and received between both the VoIP communication equipment of the call origination and call terminal during communication, and when the VoIP communication equipment on the call termination side detects the degradation of the speech quality, the IP frame including changeover request information instructing the changeover from the speech communication by the IP network to the speech communication through the PSTN is transmitted to the VoIP communication equipment on the call origination side. The VoIP communication equipment on the call origination side which receives the changeover request frame originates a phone call through the PSTN to the VoIP communication equipment on the call termination side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a communication system, a VoIP communication apparatus, and a communication method, and in particular, in VoIP communication that performs voice communication using an IP network, control capable of end-to-end communication between outgoing and incoming VoIP communication apparatuses. The present invention relates to a communication system, a VoIP communication apparatus, and a communication method capable of systematically controlling IP communication using a general IP frame.

  In recent years, so-called IP telephone based on VoIP (Voice over Internet Protocol) communication, which performs voice communication using an IP (Internet Protocol) network, has become widespread with the increase in the bandwidth of an access line network using an optical fiber cable or CATV. Yes. VoIP is a technique for packetizing voice data created by digitizing and compressing voice signals in voice communication into predetermined lengths and transmitting / receiving voice information via an IP network such as the Internet. It is. Since IP telephones can be realized with the same usage and low communication costs as communications using the existing PSTN (Public Switched Telephone Network), it has been rapidly spreading especially among companies. Yes.

  However, the IP telephone based on the packet switching system is inferior to the conventional circuit switching system PSTN telephone via the PSTN. When traffic increases due to an increase in traffic on the IP network or due to a failure in some routes, voice packets are delayed or lost, which degrades the quality of IP phone calls, making it difficult to hear or interrupting calls. There are drawbacks. Recently, these drawbacks have been resolved one after another due to the increased capacity of communication lines and the progress of voice compression technology, but it can be said that all the delays and loss of voice packets due to traffic congestion have been solved. Absent.

  In order to solve such a problem, a VoIP adapter device capable of ensuring a call quality and continuing a call without interrupting the call of the IP phone is disclosed in Japanese Patent Application Laid-Open No. 2004-165818 (Patent Document). 1). This VoIP adapter device constantly monitors an analog voice signal on the receiving side of an IP phone, and voice packets are delayed or lost due to traffic congestion of the IP network, so that the call quality deteriorates, and the deterioration is preset. If the call quality standard is exceeded, a telephone call is made via the PSTN using the telephone number of the communication partner's PSTN registered in association with the IP address, and the communication with the partner is made to the IP network. Automatically switches to a call via PSTN. As a result, the call quality can be maintained and the call can be continued.

JP 2004-165818 A

  However, the VoIP adapter device disclosed in Patent Document 1 monitors the call quality of an IP phone and switches the call from the IP network to the call via the PSTN. No consideration is given to which of the VoIP adapter device and the VoIP adapter device on the receiving side (IP receiving side) where the IP telephone call is received originates the telephone call via the PSTN. For this reason, when the IP incoming VoIP adapter apparatus detects a deterioration in call quality in the IP telephone, the IP incoming VoIP adapter apparatus may make a telephone call via the PSTN. In such a case, there is a problem that billing of a telephone call via the PSTN occurs to the VoIP adapter device on the IP terminating side that originated the telephone call.

  Further, the VoIP adapter device disclosed in Patent Document 1 does not clearly disclose the end-to-end system operation between the VoIP adapter device on the IP caller side and the VoIP adapter device on the IP callee side. In particular, it is not clear how switching from IP network to telephone call via PSTN is realized. In other words, since only one-sided operation of the VoIP adapter device on the outgoing side of a telephone call via PSTN is disclosed, the VoIP adapter device on the incoming side of a telephone call via PSTN makes a call from the IP network to the call via PSTN. There is a problem that it is not possible to determine whether to switch.

  The communication system, the VoIP communication apparatus and the communication method according to the present invention solve the above-described problem, and when the call quality deteriorates in the IP telephone using the IP network, the End-to-end VoIP communication apparatus is terminated between the outgoing and incoming VoIP communication apparatuses -To-End systematic control is executed to switch the call to a PSTN with little quality degradation to ensure the call quality, and for the telephone call via the PSTN, the VoIP communication device on the IP caller side always charges In addition, when the communication quality of the IP network improves, it is possible to switch back to the IP call again from the call via the PSTN, which is optimal in terms of both quality priority and economy, and rational for the user. It is an object to provide a communication system, a VoIP communication apparatus, and a communication method.

  The communication system, VoIP communication apparatus, VoIP communication apparatus, and communication method according to the present invention provide control information that can be transmitted / received between both VoIP communication apparatuses that are outgoing and incoming during communication in VoIP IP telephone communication using an IP network. A control IP frame including switching request information for instructing switching from a call via the IP network to a call via the PSTN when the incoming VoIP communication apparatus detects a deterioration in call quality. It transmits to the VoIP communication apparatus of the transmission side. The originating VoIP communication device that has received this switching request IP frame sends a telephone call via the PSTN to the terminating VoIP communication device. As a result, a telephone call via the PSTN can always be charged to the originating VoIP communication device.

  Specifically, each of the originating VoIP communication device and the terminating VoIP communication device transmits / receives a control IP frame and performs control of its own operation based on control information of the control IP frame. IP frame transmission / reception control means, and IP telephone number and PSTN telephone number transmitted / received to / from the other apparatus using the control IP frame, IP telephone number received from the other apparatus, and Address storage means for storing PSTN telephone numbers in correspondence with the IP addresses of the counterpart devices is provided. Then, based on the control IP frame (switching request frame) that is transmitted by the VoIP communication device on the receiving side that detects the deterioration of the call quality and includes switching request information that instructs to switch the IP call to the PSTN call, The VoIP communication device transmits a telephone call via the PSTN to the VoIP communication device on the receiving side using the PSTN call telephone number corresponding to the IP address of the called VoIP communication device stored in the address storage means. .

  In addition, when a telephone call via the PSTN is received, the incoming VoIP communication apparatus receives a telephone call via the PSTN including the telephone number for PSTN call corresponding to the IP address of the outgoing VoIP communication apparatus in the caller information. Accept calls only. Then, when the incoming VoIP communication apparatus detects the arrival of a telephone call via the PSTN, the incoming VoIP communication device sends a control IP frame (acceptance completion notification frame) including information notifying that the incoming call has been accepted. After a predetermined timing after transmitting the acceptance completion notification frame to the communication device, the call circuit in the incoming VoIP communication device is switched from the IP call to the PSTN call. On the other hand, when receiving the reception completion notification frame, the calling VoIP communication device switches the call circuit in the calling VoIP communication device from IP calling to PSTN calling. In this way, it is possible to synchronize the switching timing between outgoing and incoming calls and to secure an alternative communication path via a reliable PSTN.

  On the other hand, when the caller VoIP communication apparatus detects a deterioration in call quality, the switchover notice for notifying the callee VoIP communication apparatus to prepare for switching the IP call to the PSTN call from the caller VoIP communication apparatus. A control IP frame (switch notification frame) including information is transmitted. When receiving a control IP frame (switching notification response frame) including response information indicating that preparation for switching an IP call to a PSTN call is completed from the VoIP communication apparatus on the receiving side, the IP of the VoIP communication apparatus on the receiving side is received. Using the PSTN telephone number corresponding to the address, a telephone call via the PSTN is made to the VoIP communication apparatus on the receiving side.

  While the IP phone is switched to a PSTN call and the call is continued, the transmission analog voice signal of the call is monitored, and an IP frame including a voice packet obtained by converting the voice signal is transmitted via the IP network. The communication quality of the subsequent IP network is monitored by transmitting and receiving between the VoIP communication device on the receiving side and the VoIP communication device on the receiving side. This configuration provides an opportunity to switch back to inexpensive IP communication when the communication quality of the IP network is improved.

  When switching processing for switching an IP phone to a PSTN call is executed due to deterioration in call quality in the called VoIP communication device, and the called VoIP communication device detects an improvement in the communication quality of the IP network In this case, a control IP frame (switchback request frame) including information for requesting execution of a process for switching a PSTN call back to an IP call is transmitted to the VoIP communication device on the transmission side to trigger the switchback process. Then, when the switching process is executed due to the deterioration of the call quality in the caller VoIP communication apparatus, and the caller VoIP communication apparatus detects an improvement in the communication quality of the IP network, the PSTN call is made. A control IP frame (switchback notification frame) including information to be notified to the VoIP communication apparatus on the receiving side so as to prepare for switching back to the IP call is transmitted to the VoIP communication apparatus on the receiving side to trigger the switchback process.

When the terminating VoIP communication device transmits a switchback request frame to the originating VoIP communication device and triggers the switchback processing, the following processing is executed.
-The VoIP communication apparatus on the calling side confirms that the deterioration of the communication quality of the IP network has not been detected, and then sends a switchback notification frame for notifying the preparation to switch back the PSTN call to the IP call. To the VoIP communication apparatus.
The terminating VoIP communication apparatus transmits a control IP frame (switchback notification response frame) including response information indicating that preparation for switching back the PSTN call to the IP call is completed to the originating VoIP communication apparatus.
The originating VoIP communication device that has received the switchback notification response frame executes a process of switching back the PSTN call to the IP call.

  If the originating VoIP communication device detects deterioration when checking the communication quality of the IP network, the control IP frame (including the information for notifying the process of switching back the PSTN call back to the IP call) ( Switch-off hold notification frame) is transmitted to the VoIP communication apparatus on the receiving side. After that, when the originating VoIP communication apparatus detects an improvement in the deterioration of the communication quality of the IP network, the switch-back notification frame is transmitted to the terminating VoIP communication apparatus to proceed with the switch-back process.

  In addition, after the switch-back hold notification frame is transmitted to the VoIP communication device on the receiving side, before the switch-back notification frame is transmitted to the VoIP communication device on the call receiving side, the communication quality of the IP network is deteriorated by the VoIP communication device on the receiving side. Is detected, the VoIP communication apparatus on the receiving side transmits a control IP frame (communication quality degradation report frame) including information for reporting the cancellation of the process of switching the PSTN call back to the IP call. When receiving the control IP frame, the calling-side VoIP communication apparatus stops executing the switch-back process.

When the originating VoIP communication device transmits a switchback notification frame to the terminating VoIP communication device and triggers the switchback processing, the following processing is executed.
The incoming call side VoIP communication apparatus confirms that the deterioration of the communication quality of the IP network has not been detected, and a switchback notification response frame including response information notifying that preparation for switching back the PSTN call to the IP call has been completed. Send.
Upon receiving this switchback notification response frame, the calling-side VoIP communication apparatus executes a process of switching back the PSTN call to the IP call.

  When the incoming VoIP communication device detects deterioration when checking the communication quality of the IP network, the control VoIP communication device includes information for notifying that the process of switching the PSTN call back to the IP call is suspended ( Switch-back hold request frame) is transmitted to the VoIP communication device on the caller side. After that, when the incoming VoIP communication apparatus detects an improvement in the deterioration of the communication quality of the IP network, a return notification response frame is transmitted to the outgoing VoIP communication apparatus to proceed with the return processing.

  In addition, after the switchback hold request frame is transmitted to the VoIP communication device on the caller side, before the switchback notification response frame is transmitted to the VoIP communication device on the caller side, the VoIP communication device on the caller side determines the communication quality of the IP network. When the deterioration is detected, the VoIP communication apparatus on the transmission side transmits a control IP frame (communication quality deterioration report frame) including information for reporting the cancellation of the process of switching the PSTN call back to the IP call. When receiving the control IP frame, the called-side VoIP communication device stops executing the switch-back process.

  Since a control IP frame that can be controlled end-to-end is used between both outgoing and incoming VoIP communication devices, if the call quality deteriorates in an IP telephone using an IP network, the end-to-to -System control at the end can be executed. As a result, it is possible to switch the call to a PSTN with little quality degradation to ensure the call quality, and to always charge the telephone call via the PSTN by the VoIP communication device on the IP transmission side. When the communication quality is improved, it is possible to switch back to the IP call again from the call via the PSTN.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a system configuration diagram showing an embodiment of a communication system according to the present invention.

  The communication system according to the present invention includes an VoIP communication apparatus 100 for connecting an IP telephone 106 composed of an analog telephone and a PC (Personal Computer) to an IP network 105 and a PSTN 104 via an IP line 103 and a PSTN line 102, respectively. An IP telephone 107 composed of an analog telephone and a PC is composed of a VoIP communication apparatus 101 that is connected to an IP network 105 and a PSTN 104 via an IP line 103 and a PSTN line 102, respectively. The IP phone 106 and the IP phone 107 are connected to the SIP call via a SIP (Session Initiation Protocol) server (not shown) normally installed in the IP network 105 by the VoIP communication device 100 and the VoIP communication device 101 respectively connected thereto. The IP telephone call is set and disconnected by the control, and IP telephone communication by VoIP communication according to RTP (Real-time Transport Protocol) is performed. Each VoIP communication apparatus 100, 101 is assigned an IP telephone number in the IP network and a PSTN telephone number in the PSTN.

2 and 3 are block configuration diagrams showing the device configurations of the VoIP communication device 100 and the VoIP communication device 101, respectively. Since both VoIP communication devices have the same device configuration, the device configuration of the VoIP communication device 100 will be described with reference to FIG. (Regarding the device configuration of the VoIP communication device 101, the corresponding reference symbols may be replaced.)
The VoIP communication apparatus 100 includes a telephone interface unit 200 that connects analog telephones constituting the IP telephone 106, a PSTN interface unit 201 that connects to the PSTN line 102, a WAN (Wide Area Network) interface unit 202 that connects to the IP line 103, IP It has an interface unit that connects to four external parts of a LAN (Local Area Network) interface unit 203 that connects to a PC that constitutes the telephone set 106.

  As an internal configuration, a main control unit 208 that controls each unit constituting the apparatus to execute processing control according to the present invention, which will be described later, and a PSTN telephone number assigned by the PSTN of the IP telephone communication partner is used. Address storage unit 207 that registers and manages the IP address and IP telephone number in correspondence with each other, Ethernet peripheral circuit unit 209 that transmits and receives IP frames to and from IP network 105 via WAN interface unit 202, and communication control related to IP telephone communication A VoIP peripheral circuit unit 206 that performs voice packet / voice signal conversion, a PSTN peripheral circuit unit 205 that controls outgoing and incoming PSTN telephone calls to the PSTN 104 via the PSTN interface unit 201, and an IP phone via the IP network 105 Line switching unit 2 for switching between communication and PSTN telephone communication via PSTN 104 It is equipped with a 4.

  In addition, said structure shows the main components which concern on this invention, Description and description are abbreviate | omitted about the other component which is not related to this invention.

  Further, although the IP telephones 106 and 107 are described as being constituted by analog telephones and PCs, they may be constituted only by analog telephones. In that case, the LAN interface unit in the VoIP communication apparatus may not be provided.

  In the above configuration, an outline operation in the case of performing IP telephone communication as a premise of the present invention will be described.

  Call control information (for example, a call signal and a destination telephone number) operated on an analog telephone of the IP telephone 106 on the calling side is transmitted to the VoIP peripheral circuit section via the telephone interface section 200 and the line switching section 204 of the VoIP communication apparatus 100. An IP frame is generated in accordance with a protocol (in this embodiment, described as SIP) necessary for call control of IP telephone communication under the control of the main control unit 208 and is generated by the Ethernet peripheral circuit unit 209 and the WAN interface unit 202 to be transmitted to a SIP server (not shown) of the IP network 105.

  On the other hand, the VoIP communication apparatus 101 on the receiving side performs main control of a call control IP frame (for example, a call request) transmitted from a SIP server (not shown) of the IP network 105 via the WAN interface unit 302 and the Ethernet peripheral circuit unit 300. When received by the unit 308, it is converted into information for controlling the analog telephone of the IP telephone 107 under the control of the VoIP peripheral circuit unit 306, and sent to the telephone interface unit 300 via the line switching unit 304. At the same time, the main control unit 308 and the VoIP peripheral circuit unit 306 send an IP frame including call control information indicating that the call is being performed to the SIP server (not shown) of the IP network 105 via the Ethernet peripheral circuit unit 300 and the WAN interface unit 302. Return to

  Through the above operation, the telephone interface unit 300 of the VoIP communication apparatus 101 on the receiving side issues an instruction to ring the ringing tone of the IP telephone 107 (analog telephone). When the VoIP communication apparatus 100 on the caller side receives an IP frame including call control information indicating that the callee is ringing from the SIP server, the telephone interface unit 200 makes a ringing tone to the analog telephone of the IP telephone 106 ( Ring back tone).

  When the IP telephone 107 responds, an IP frame including call control information indicating a successful call is sent from the VoIP communication apparatus 101 on the receiving side to the VoIP communication apparatus 100 on the calling side via a SIP server (not shown) of the IP network 105 as described above. Further, the acknowledgment information is sent back from the VoIP communication apparatus 100 on the transmission side to the VoIP communication apparatus 101 on the reception side via the SIP server (not shown) of the IP network 105, whereby the IP telephone set 106 and the IP telephone set 107 Call state is entered.

  When the communication state is established, the VoIP peripheral circuit units 206 and 306 of the respective VoIP communication apparatuses 100 and 101 perform the conversion process of the voice signal / voice packet with respect to the IP frame including the voice packet transmitted and received by End-to-End. The IP frame is assembled / disassembled under the control of the main control unit 208. In addition, transmission / reception of voice packets is controlled according to RTP.

  After receiving the call information of IP telephone communication in the VoIP communication device 100 on the calling side, and after receiving the call control IP frame (for example, a call request) from the SIP server in the VoIP communication device 101 on the receiving side, In order not to accept the incoming call of the PSTN communication via the PSTN 104, each main control unit 208, 308 sends a blocking signal from the PSTN interface unit 201, 301 to the PSTN peripheral circuit unit 205, 305 to the PSTN 104. Instructed to send. In other words, when IP telephone communication via the WAN interface units 202 and 302 is started, the PSTN interface units 201 and 301 are blocked to prevent double connection due to incoming telephone calls from the PSTN.

  Next, the operation of the embodiment of the present invention will be described in detail with reference to the sequence diagram shown in FIG.

  In the present invention, the IP telephone communication by the IP network 105 is established, and control is performed at the start or during transmission / reception of an IP frame including an end-to-end voice packet between the VoIP communication apparatuses 100 and 101. An IP frame including information is transmitted and received between the VoIP communication apparatuses 100 and 101. The IP frame including the control information is generated and interpreted by the main control units 208 and 308 of the VoIP communication devices 100 and 101, and is used for control of each internal component device by the main control units 208 and 308. Therefore, for example, control information packets can be generated by adding identification information that distinguishes them from voice packets to a UDP (User Datagram Protocol) header, and can be assembled into an IP frame and transmitted / received via the IP network 105. In the following description, this IP frame is referred to as a control IP frame.

  In FIG. 4, from step 400 to step 401, the call control using the SIP server described above causes the caller VoIP communication apparatus 100 and the callee VoIP communication apparatus 101 to be in an IP telephone communication state via the IP network 105. This is simply shown.

  When IP telephone communication via the IP network 105 is established, the VoIP communication apparatus 100 on the transmission side transmits the above-described control IP frame including the IP telephone number 100A and the PSTN telephone number 100B assigned to the own apparatus to the IP network 105. Is transmitted to the VoIP communication apparatus 101 on the receiving side via (step 402).

  The VoIP communication apparatus 101 on the receiving side that has received this control IP frame interprets the contents in the main control apparatus 308, and sets the IP telephone number 100A and PSTN telephone number 100B of the received VoIP communication apparatus 100 on the call side as call settings. Sometimes, the IP address of the originating VoIP communication apparatus 100 notified from the SIP server is registered in the address storage unit 307 in correspondence with the IP address (step 403).

  In addition, the VoIP communication device 101 on the receiving side generates a control IP frame including the IP phone number 101A and PSTN phone number 101B of the own device as a response to the control IP frame received from the VoIP communication device 100 on the outgoing side. Then, the data is transmitted to the VoIP communication apparatus 100 on the caller side via the IP network 105 (step 404).

  The originating VoIP communication device 100 interprets the contents in the main control device 208, and the received IP phone number 101A and PSTN phone number 101B of the receiving VoIP communication device 101 are notified from the SIP server at the time of call setup. The received address is registered in the address storage unit 207 in correspondence with the IP address of the incoming VoIP communication apparatus 101 (step 405).

  FIG. 6 is a conceptual diagram showing how the VoIP communication apparatuses 100 and 101 mutually notify the IP telephone number and the PSTN telephone number using the control IP frame, and store them in the address storage units 207 and 307, respectively. It is the schematic diagram shown.

  When the mutual notification of the IP telephone number and the PSTN telephone number assigned to each VoIP communication apparatus 100, 101 is completed, each VoIP communication apparatus 100, 101 sets the IP telephone to a call state, and the IP telephone 106 and IP IP telephone communication by the telephone 107 via the IP network 105 is started (step 406).

  In this embodiment, for convenience of explanation, a case has been described in which the mutual notification of the IP telephone number and the PSTN telephone number is performed prior to the start of the call. However, the mutual notification of the IP telephone number and the PSTN telephone number is performed before the call starts. It is not limited and may be performed during a call. However, it is preferable to carry out at an early time after the start of a call.

  The main control unit of the VoIP communication apparatus constantly monitors the communication quality (IP frame delay or disappearance) of IP frames including voice packets during IP telephone communication. In order to determine the call quality in IP telephone communication, a predetermined communication quality standard is registered in advance. That is, in the present invention, the IP telephone call quality is determined in association with the IP frame communication quality in the IP network.

  Assume that IP frame delay or loss occurs due to traffic congestion in the IP network 105 during IP telephone communication, and the main control unit 308 of the VoIP communication apparatus 101 on the receiving side detects deterioration in communication quality.

  When the main control unit 308 of the called-side VoIP communication apparatus 101 detects that the monitored communication quality has deteriorated and has become larger than the registered communication quality standard, the call quality of the IP phone Therefore, the calling side VoIP communication apparatus 100 is requested to switch the current call to the call via the PSTN 104, which is a circuit switching network in which communication quality is guaranteed, not via the IP network 105.

  Specifically, the main control unit 308 of the called-side VoIP communication apparatus 101 executes switching from IP telephone communication via the IP network 105 to a PSTN call via the PSTN 104 to the calling-side VoIP communication apparatus 100 of the communication partner. do that for me. For this purpose, a control IP frame (switching request frame) including information to that effect is generated and transmitted to the VoIP communication apparatus 100 on the caller side via the IP network 105 (step 407). At this time, the main control unit 308 releases the blocking of the PSTN interface unit 301 that is blocked at the start of the IP telephone communication in order to accept the incoming call by the PSTN communication. That is, the main control unit 308 instructs the PSTN peripheral circuit unit 305 to stop the block signal transmitted from the PSTN interface unit 301 to the PSTN 104.

  The main control unit 208 of the originating VoIP communication device 100 that has received the switching request frame from the terminating VoIP communication device 101 stores the communication partner in the address storage unit 207 based on the IP address of the communication partner that can be identified from the switching request frame. The PSTN telephone number 101B assigned to the VoIP communication apparatus 101 on the receiving side registered in correspondence with the IP address is read out. Then, the PSTN peripheral circuit unit 206 is instructed to make a PSTN call using the PSTN telephone number 101B to the PSTN 104 (step 408).

  The PSTN peripheral circuit unit 205 that has received the PSTN call origination instruction uses the PSTN telephone number 101B of the VoIP communication apparatus 101 on the receiving side instructed from the main control unit 208, and the PSTN 104 via the PSTN interface unit 201. A telephone call is made (step 409).

  Further, the main control unit 208 of the originating VoIP communication apparatus 100 that has instructed the PSTN peripheral circuit unit 206 to make a PSTN call to the PSTN 104 makes a PSTN 104 to the terminating VoIP communication apparatus 101 according to the switching request. Then, a control IP frame (PSTN call notification frame) including information notifying that a PSTN call has been sent via is transmitted (step 410).

  As described above, since the PSTN telephone call originated from the VoIP communication device 100 on the originating side is released from the blocking of the PSTN interface unit 301 with respect to the PSTN 104 in the VoIP communication device 101 on the terminating side, the VoIP communication on the terminating side is performed. An incoming call arrives at the device 101.

  At this time, the VoIP communication apparatus 101 on the receiving side needs to receive only PSTN call calls intended for switching the IP telephone communication transmitted from the VoIP communication apparatus 100 on the calling side. Therefore, the VoIP communication apparatus 101 on the receiving side performs caller number identification for the PSTN call that has arrived at the PSTN interface unit 301.

  The main control unit 308 of the called-side VoIP communication apparatus 101 sends the caller information (PSTN telephone number of the caller) included in the incoming call information of the PSTN call received by the PSTN peripheral circuit unit 305 via the PSTN interface unit 301. Is compared with the PSTN telephone number assigned to the VoIP communication apparatus 100 of the other party of the IP telephone communication stored in the address storage unit 307 when the IP telephone communication is established. Control to accept.

  Further, the fact that the PSTN call notification frame transmitted from the VoIP communication device 100 on the caller side is received may be added to the incoming condition for the PSTN call.

  When a PSTN call originated from the originating VoIP communication device 100 is received via the PSTN interface unit 301 and the PSTN peripheral circuit unit 305, the main control unit 308 of the terminating VoIP communication device 101 receives the control IP frame. (Reception completion notification frame) is transmitted to the VoIP communication device 100 on the transmission side (step 411). This acceptance completion notification frame accepts an incoming PSTN telephone call for an alternative call originated by the caller VoIP communication device 100, and sets a PSTN between the caller VoIP communication device 100 and the callee VoIP communication device 101. This is information notifying that an alternative communication path has been formed.

  The main control unit 208 of the originating VoIP communication apparatus 100 that has received the reception completion notification frame switches the connection of the line switching unit 204 from the connection via the IP network 105 to the connection via the PSTN 104 via the PSTN interface unit 201. Do.

  In addition, the main control unit 308 of the incoming-side VoIP communication apparatus 101 transmits the reception completion notification frame and then connects the line switching unit 304 via the IP network 105 after a delay time that can be predicted by the RTP transmission / reception cycle has elapsed. Switching from connection to connection via the PSTN 104 via the PSTN interface unit 301 is performed. This is because the IP frame including the voice packet conforming to RTP is repeatedly transmitted and received at a cycle of 10 ms / 20 ms. Therefore, the incoming VoIP communication apparatus 101 determines how much delay after transmitting the reception completion notification frame. This means that the VoIP communication device 100 on the transmission side knows whether or not to receive the reception completion notification frame after the time.

  As a result, the calling-side VoIP communication apparatus 100 and the called-side VoIP communication apparatus 101 can synchronize and switch the call line from the IP network 105 to the PSTN 104, and the call quality is maintained without any discomfort for the user. The call can be continued (step 412).

  As described above, in the communication system according to the present invention, even when communication quality degradation is detected by the incoming VoIP communication apparatus 101, the incoming VoIP communication apparatus 101 switches to the PSTN call. Since the PSTN call is requested from the originating VoIP communication device 100, a VoIP communication system that can always charge only the originating VoIP communication device 100 can be realized.

  Note that the above description is based on the PSTN call so that the calling side VoIP communication device 100 is always charged even when the degradation of the communication quality during the IP telephone communication is detected by the called side VoIP communication device 101. Described from the perspective of placing a call.

  Next, a case where the transmission side VoIP communication apparatus 100 detects deterioration of communication quality during IP telephone communication will be described with reference to the sequence diagram shown in FIG. In this case, since the VoIP communication apparatus 100 on the calling side actively sends a PSTN call, the charging for the PSTN call is naturally made to the VoIP communication apparatus 100 on the calling side.

  FIG. 5 establishes the IP telephone communication described with reference to FIG. 4 (step 401), and notifies the IP telephone number and PSTN telephone number between the VoIP communication apparatuses 100 and 101 (steps 402 and 404). The sequence from the operation (step 406) during the call through the IP network 105 after the operation (steps 403 and 405) for registering the information in the address storage units 207 and 307 is completed is shown.

  When it is detected that the communication quality monitored by the main control unit 208 of the originating VoIP communication apparatus 100 has deteriorated and becomes larger than the registered communication quality standard (step 501), In order to maintain the call quality, the control unit 208 switches the current call to a call via the PSTN 104, which is a circuit switching network in which the communication quality is guaranteed, not via the IP network 105. Notify the device 101. Specifically, the main control unit 208 of the calling-side VoIP communication apparatus 100 prepares for the switching to the PSTN call via the PSTN 104 from the IP telephone communication by the IP network 105 to the receiving-side VoIP communication apparatus 101. In order to be executed, a control IP frame (switch notification frame) including information to that effect is generated and transmitted to the VoIP communication apparatus 101 on the receiving side via the IP network 105 (step 502).

  The main control unit 308 of the called-side VoIP communication apparatus 101 that has received this switching notification frame sends an instruction to release the blocked state of the PSTN interface unit 301 to the PSTN peripheral circuit unit 306 so that the PSTN incoming call can be received (step). 503). The main control unit 308 that has instructed to release the blocking of the PSTN interface unit 301 transmits a control IP frame (switching notification response frame) including information indicating that the preparation for incoming PSTN has been completed to the originating VoIP communication apparatus 100 ( Step 504).

  The subsequent operation is the same as the operation after step 408 in FIG.

  When receiving the switching notification response frame, main controller 208 of calling-side VoIP communication apparatus 100 receives the incoming call registered in address storage unit 207 in correspondence with the IP address of the communication partner based on the IP address of the communication partner. The PSTN telephone number 101B of the VoIP communication apparatus 101 on the side is read, and the PSTN peripheral circuit unit 206 is instructed to make a PSTN call using the PSTN telephone number 101B to the PSTN 104 (step 506).

  The PSTN peripheral circuit unit 205 that has received a PSTN call calling instruction sends a telephone call to the PSTN 104 via the PSTN interface unit 201 using the PSTN telephone number 101B instructed by the main control unit 208 (step ST). 507).

  In addition, the main control unit 208 of the originating VoIP communication device 100 that has instructed the PSTN peripheral circuit unit 206 to make a PSTN call to the PSTN 104, with respect to the terminating VoIP communication device 101 via the PSTN 104. A control IP frame (PSTN call notification frame) including information notifying that a PSTN call has been sent is transmitted (step 508).

  As described with reference to FIG. 4, the PSTN call originated from the originating VoIP communication apparatus 100 arrives at the PSTN interface 301 of the terminating VoIP communication apparatus 101 and receives the incoming PSTN call. Only when the PSTN telephone number of the caller included in the call information matches the PSTN telephone number of the VoIP communication apparatus 100 of the IP telephone communication partner stored in the address storage unit 307 when the IP telephone communication is established, Accepted.

  Then, the main control unit 308 of the incoming VoIP communication apparatus 101 transmits a control IP frame (acceptance completion notification frame) for notifying that the incoming PSTN call has been recognized to the outgoing VoIP communication apparatus 100. (Step 509).

  The main control unit 208 of the originating VoIP communication apparatus 100 that has received the reception completion notification frame switches the connection of the line switching unit 204 from the connection via the IP network 105 to the connection via the PSTN 104 via the PSTN interface unit 201. Do.

  In addition, the main control unit 308 of the incoming-side VoIP communication apparatus 101 transmits the reception completion notification frame and then connects the line switching unit 304 via the IP network 105 after a delay time that can be predicted by the RTP transmission / reception cycle has elapsed. Switching from connection to connection via the PSTN 104 via the PSTN interface unit 301 is performed.

  As a result, the calling-side VoIP communication apparatus 100 and the called-side VoIP communication apparatus 101 can synchronize and switch the call line from the IP network 105 to the PSTN 104, and the call quality is maintained without any discomfort for the user. The call can be continued (step 510).

  As described above, the communication system according to the present invention establishes IP telephone communication over the IP network 105 and transmits / receives IP frames including end-to-end voice packets between the VoIP communication apparatuses 100 and 101. The control IP frame including the control information can be transmitted / received between the respective VoIP communication devices 100 and 101 at the start or during transmission / reception. Therefore, when the deterioration of the communication quality is detected during the IP telephone communication, the originating side VoIP communication apparatus 100 transmits the PSTN call by sending a switching request frame or a switching notification frame to the other party VoIP communication apparatus. The call can be switched to a PSTN call to continue the call. For this reason, even if communication quality degradation is detected in the incoming VoIP communication apparatus 101, the outgoing VoIP communication apparatus 100 issues a PSTN call and switches the IP call to the PSTN call. The VoIP communication apparatus 101 is not charged.

  Thus, the communication system according to the present invention can realize a VoIP communication system that is quality-first and reasonable for the user.

  In the above description, the control for switching to the PSTN call when the quality of the IP call deteriorates has been described. The IP telephone communication path via the switched IP network 105 may be disconnected. In that case, the call-side VoIP communication apparatus 100 transmits a call control IP frame (disconnect request) to a SIP server (not shown), so that the same call control is performed from the SIP server to the call-receiving VoIP communication apparatus 101. A disconnection instruction is issued by the IP frame, and the IP telephone communication path is disconnected according to a prescribed protocol. Subsequent calls are PSTN calls via the PSTN 104.

  However, the communication system of the present invention holds the IP telephone communication path as it is so that the PSTN call can be switched to the IP call again when the quality of the IP communication is recovered after the transition to the PSTN call. You can also. That is, by using IP telephone communication excellent in economy as much as possible, an optimal communication system can be realized in terms of both quality priority and economy. Examples thereof will be described below.

  In order to switch the PSTN call to the IP call again when the quality of the IP communication is restored, it is necessary to hold the IP telephone communication path via the IP network 105 and constantly monitor the communication quality. Therefore, the communication system according to the present invention continues to transmit and receive voice packets between the VoIP communication apparatuses 100 and 101.

  Voice packets transmitted / received between the VoIP communication devices 100 and 101 are transmitted / received for the purpose of monitoring communication quality by transmitting / receiving IP frames, and are not used for actual communication. Therefore, a method of transmitting and receiving dummy voice packets terminated between the main control units 208 and 308 of the respective VoIP communication apparatuses 100 and 101 may be used. That is, after switching to the PSTN call, the functions of the respective VoIP peripheral circuits 206 and 306 are stopped, the main control units 208 and 308 generate and transmit IP frames including dummy voice packets, and are received. Control to discard the dummy voice packet is executed. If this method is adopted, the conversion of the voice packet / voice signal in the VoIP peripheral circuit becomes unnecessary, and the processing load of the entire VoIP communication apparatus is reduced accordingly.

  However, here, a method for continuously transmitting / receiving actual voice packets, which can relatively easily control switching back to an IP call, will be described.

  The line switching units 204 and 304 of the respective VoIP communication devices 100 and 101 not only switch the audio signal path connected to the telephone interface units 200 and 300, but also the signal path of the transmission side audio signal is changed to the PSTN interface unit 201. At the same time, the transmission side audio signal is transmitted to the VoIP peripheral circuits 206 and 306 through the branched signal path. In addition, the signal path of the reception side voice signal converted into the voice packet / voice signal by the VoIP peripheral circuits 206 and 306 is terminated by the pseudo-receiving circuit in the line switching units 204 and 304 after switching to the PSTN call. .

  FIG. 7 is a block diagram conceptually showing the related circuit configuration of the line switching units 204 and 304.

  The transmission side audio signal path connected to the telephone interface units 200 and 300 is divided into two directions by the branch circuit 701, and the transmission side audio signal is transmitted only to the VoIP peripheral circuits 206 and 306 during the IP call. When an instruction to switch from an IP call to a PSTN call is issued from the main control units 208 and 308, a transmission side audio signal is transmitted to the PSTN interface units 201 and 301 by the switching circuit 702.

  In addition, the signal path of the reception-side audio signal converted into the audio packet / audio signal by the VoIP peripheral circuits 206 and 306 is connected to the telephone interface units 200 and 300 during the IP call. When an instruction to switch from an IP call to a PSTN call is issued from the main control units 208 and 308, the signal path of the reception side audio signal from the VoIP peripheral circuit is terminated by the pseudo reception circuit by the switching circuit 702, and the PSTN interface unit 201 , 301 are connected to the telephone interface units 200 and 300.

  Since the line switching units 204 and 304 are configured as described above, the call voice between the VoIP communication devices 100 and 101 is voice packets / voice signals in the VoIP peripheral circuits 206 and 306 even after switching to the PSTN call. After being converted, the IP frame is transmitted / received via the IP network 105. Since it is not used for an actual call, the voice packet received by each of the VoIP communication apparatuses 100 and 101 is converted into a voice signal and then terminated in the pseudo-receiving circuit 703 of the line switching units 204 and 304.

  Since the above-described configuration is adopted, the main control units 208 and 308 of the respective VoIP communication apparatuses 100 and 101 perform communication due to delay or loss of IP frames transmitted / received via the held IP network 105 even during a PSTN call. Quality can be monitored constantly.

  Next, the operation when the communication quality of the IP network 105 is detected as a result of monitoring the communication quality by the main control units 208 and 308 will be described. It is detected that the communication quality of the IP network 105 is improved so that the communication quality of the IP network 105 satisfies the condition for returning to the predetermined IP network 105 and the state continues for a predetermined time. .

  When the call is switched to the PSTN 104 due to the deterioration of the communication quality of the IP network 105, the call quality of the transmission side voice and the reception side voice is secured in the IP network 105 as a condition for switching the call back to the IP network 105 again. As a condition. Therefore, when a call is switched to the PSTN 104 based on a request for switching the incoming VoIP communication apparatus 101, a call-back request is received from the incoming VoIP communication apparatus 101 and monitored by the outgoing VoIP communication apparatus 100. Check the communication quality. When the caller VoIP communication apparatus 100 detects a deterioration in communication quality and switches the call to the PSTN 104, the call quality monitored by the callee VoIP communication apparatus 101 is confirmed.

  Details of the operation for switching back to the IP call after switching to the PSTN call will be described with reference to FIGS. Each frame in the figure includes control information that is transmitted and received at the end-to-end between the VoIP communication apparatuses 100 and 101 described above, and is generated and interpreted by the main control units 208 and 308, respectively. It is a control IP frame.

  FIGS. 8 to 10 are sequence diagrams of switching operation when a call is switched to the PSTN 104 based on a switching request from the incoming VoIP communication device 101, an operation flowchart of the outgoing VoIP communication device 100, and incoming VoIP communication. 3 is an operation flowchart of the apparatus 101. 9 to 11 are sequence diagrams of switching operation when the caller VoIP communication apparatus 100 detects a deterioration in communication quality and switches the call to the PSTN 104, an operation flowchart of the caller VoIP communication apparatus 100, and 5 is an operation flowchart of the VoIP communication apparatus 101 on the receiving side.

  First, with reference to FIGS. 8 to 10, a description will be given of a switch back operation when a call is switched to the PSTN 104 based on a switching request from the incoming VoIP communication apparatus 101. FIG. 8 shows three operations (a) to (c).

  Step 800 and Step 801 in FIG. 8A are the PSTN call after switching from the IP call to the PSTN call by the above-described operation, and the IP communication (monitored) for the purpose of monitoring the communication quality of the IP network 105. (Transmission and reception of IP frames including voice packets). In such a state, it is assumed that an improvement in communication quality of the IP network 105 is detected in the incoming VoIP communication apparatus 101 that has been monitoring the communication quality (step 802).

  Each of the VoIP communication devices 100 and 101 stores which request is executed to switch from the IP call to the PSTN call. That is, whether the incoming side VoIP communication apparatus 101 detects a deterioration in communication quality and makes a switching request, or whether the outgoing side VoIP communication apparatus 100 detects a change in communication quality and switches it. I remember it. Then, the VoIP communication apparatus that has become the switching subject triggers a switchback.

  Therefore, even if a deterioration in communication quality is detected or improved in the VoIP communication apparatus that is not the switching subject during the communication quality monitoring of the IP network 105 during the PSTN call, a trigger for switching back If no is applied, no action is taken. For example, when the incoming VoIP communication apparatus 101 detects a deterioration in communication quality and issues a switching request, the call is switched to a PSTN call. In the communication quality monitoring of the IP network 105 during the PSTN call, Even if the communication quality degradation is detected by the VoIP communication apparatus 100 on the side, if the trigger for switching back is not applied, it is not notified to the VoIP communication apparatus 101 on the receiving side. Accordingly, even if an improvement in communication quality is subsequently detected by the originating VoIP communication apparatus 100, the same applies.

  Accordingly, in the case of FIG. 8, since the sequence diagram of the switch back operation when the call is switched to the PSTN 104 based on the switch request of the call receiving side VoIP communication device 101, the call receiving side VoIP communication device 101 triggers the switch back. ing. Then, as the communication quality of the IP network 105 is improved, the VoIP communication apparatus 101 on the receiving side receives a control IP frame (information for switching back) including information requesting to switch the currently connected PSTN call back to the IP call. Frame) is transmitted to the VoIP communication apparatus 100 on the transmission side (step 803).

  Upon receiving the switchback request frame, the originating VoIP communication apparatus 100 confirms that there is no detection of deterioration in the communication quality monitored by itself (step 804), and switches back from the PSTN call to the IP call. A control IP frame (switchback notification frame) for notifying execution is transmitted to the VoIP communication apparatus 101 on the receiving side to instruct preparation for switchback to the IP call (step 805).

  Upon receiving the switchback notification frame from the caller VoIP communication apparatus 100, the callee VoIP communication apparatus 101 prepares to switch back to the IP call (step 806), and notifies the control IP that the preparation has been completed. The frame (switchback notification response frame) is transmitted to the VoIP communication device 100 on the transmission side (step 807).

  Here, preparation for switching back to an IP call refers to switching from a PSTN call to an IP call in the line switching unit 304 after a certain timing after the switch-back notification response frame is transmitted to the VoIP communication device 100 on the caller side. And instructing the PSTN peripheral circuit unit 305 to close the PSTN line when the PSTN line disconnection signal is detected by the PSTN interface unit 301. Therefore, when the line switching unit 304 is switched, the line switching unit 304 disconnects the connection to the PSTN interface unit 301 and receives from the VoIP peripheral circuit unit 306 as described with reference to FIG. The side audio signal path is disconnected from the pseudo-receiving circuit 703 and connected to the telephone interface unit 300.

  On the other hand, when the switchback notification response frame is received, the VoIP communication device 100 on the calling side performs switchback processing to the IP call in the own device (step 808).

  The switch-back processing in the originating VoIP communication apparatus 100 is performed by switching the PSTN call from the PSTN call to the IP call by the line switching unit 204, sending a PSTN line disconnection signal by the PSTN interface unit 201, and then the PSTN. This is to instruct the PSTN peripheral circuit unit 205 to block the line.

  When the above processing is completed, the IP call state is established (step 809), and the PSTN call is disconnected (step 810).

  As described above, the switch-back process is a process of switching the already prepared speech path and disconnecting one of the speech paths. In the case of the switching process, the PSTN transmission notification frame and the reception completion notification frame are transmitted and received when the PSTN communication path is set, and the switching control is executed. It is controlled by a switchback notification frame and its response frame. Therefore, transmission / reception of the control IP frame at the time of disconnection of the communication path is particularly necessary.

  Next, referring to FIG. 8 (b), in the originating VoIP communication apparatus 100 that has received the switchback request frame from the terminating VoIP communication apparatus 101, a deterioration is detected in the communication quality monitored by the own apparatus. The operation in the case of having been performed will be described. In this case, even if the call is switched back to the IP call, the call quality is deteriorated in the caller-side VoIP communication apparatus 100, so the meaning of the switch back is lost. Therefore, the switch-back process is temporarily suspended.

  The originating VoIP communication device 100 that has received the switchback request frame (step 803) transmitted from the terminating VoIP communication device 101 checks whether or not the communication quality monitored by the own device has deteriorated. If communication quality degradation is detected (step 820), the originating VoIP communication apparatus 100 receives a control IP frame (switchback hold notification frame) for notifying that the requested switchback process is to be held. To the VoIP communication apparatus 101 on the side.

  The incoming VoIP communication device 101 that has received the switch-back hold notification frame waits until the next notification from the outgoing VoIP communication device 100 is received. Even during this waiting time, the VoIP communication apparatus 101 on the receiving side continues to monitor the communication quality in the own apparatus.

  When it is determined that the communication quality monitored in the VoIP communication device 100 on the calling side has improved and switching back to the IP call is possible (step 821), the VoIP communication device 100 on the calling side returns to the PSTN. A control IP frame (switchback notification frame) for notifying that the switchover from the call to the IP call is executed is transmitted to the VoIP communication apparatus 101 on the receiving side to instruct the preparation for the switchback to the IP call (step) 805). The subsequent operation is the same as the operation after step 806 in FIG.

  As described above, even if a switchback request is received from the VoIP communication apparatus 101 on the receiving side, the switch back to the IP call is not performed as long as the communication quality deterioration is detected in the VoIP communication apparatus 100 on the calling side. .

  Next, with reference to FIG. 8C, description will be given of an operation in the case where deterioration is detected in the communication quality monitored by the VoIP communication apparatus 101 on the receiving side during the above-described switching back hold.

  As described with reference to FIG. 8B, even when a switchback request is received from the incoming VoIP communication apparatus 101, if the communication quality deterioration is detected in the outgoing VoIP communication apparatus 100 (step 820), the disconnection request is made. A return hold notification frame is transmitted to the VoIP communication apparatus 101 on the receiving side (step 821), and the switchback is held. Even during the hold, the VoIP communication apparatus 101 on the receiving side continues to monitor the communication quality in the own apparatus.

  If the incoming VoIP communication apparatus 101 detects a deterioration in communication quality while the return is on hold (step 830), even if the communication quality is improved in the outgoing VoIP communication apparatus 100, the call is switched back to the IP call. Meaning disappears. Therefore, the VoIP communication apparatus 101 on the receiving side transmits a control IP frame (communication quality deterioration report frame) for reporting that the communication quality being monitored has deteriorated to the VoIP communication apparatus 100 on the calling side (step 831). ).

  The communication quality deterioration report frame means that the switch-back process to the triggered IP call is stopped. Therefore, the IP VoIP communication device 101 that has transmitted the communication quality degradation report frame and the originating VoIP communication device 100 that has received the communication quality degradation report frame stop the switch-back processing to the IP call (step 830). Step 832).

  After canceling the switchback process, the VoIP communication apparatuses 100 and 101 return to the IP communication quality monitoring state.

  FIG. 9 shows the operation of the originating VoIP communication apparatus 100 in the switch back processing when the call is switched to the PSTN 104 based on the switching request of the terminating VoIP communication apparatus 101 described above. The operation 101 is shown in the flowchart of FIG.

  FIG. 9 is a flowchart showing the operation of the calling-side VoIP communication apparatus 100 in the switch-back process described with reference to FIG.

  In FIG. 9, when a switchback request frame is received from the VoIP communication apparatus 101 on the receiving side (step 900), the quality of the reception quality monitored by the own apparatus is confirmed (step 901).

  If it is confirmed that the reception quality monitored by the own device is good (step 901: YES), a switchback notification frame is transmitted to the VoIP communication device 101 on the receiving side (step 902). Waiting for a response from the incoming VoIP communication device 101 (step 903) and receiving a switchback notification response frame from the incoming VoIP communication device 101 (step 903: YES), an IP call in the incoming VoIP communication device 101 Knowing that the preparation for switching back to IP is completed, the switch-back processing to the IP call in the own apparatus is executed as described in FIG. 8A (step 904).

  On the other hand, as described in FIG. 8B, when it is confirmed that the reception quality monitored by the own apparatus is good or bad (step 901: NO), the incoming side A switchback hold notification frame is transmitted to the VoIP communication apparatus 101 to notify the temporary hold of switchback processing (step 905). Thereafter, the reception quality improvement status in the own apparatus is monitored (step 906).

  When the reception quality improvement in the own device is detected (step 906: YES), the processing returns to step 902 to transmit a switchback notification frame to the VoIP communication device 101 on the receiving side in order to continue the held back switchback processing. . Subsequent processing is as described above.

  In addition, while monitoring the reception quality improvement status in the own device, the presence / absence of a deterioration report from the VoIP communication device 101 on the receiving side is confirmed (step 907). If a deterioration report is received from the VoIP communication apparatus 101 on the receiving side during this monitoring (step 907: YES), the switch-back process is stopped. This processing corresponds to that described with reference to FIG.

  Similarly, the operation of the VoIP communication apparatus 101 on the receiving side in the switch-back process described in FIG. 8 will be described with reference to the flowchart in FIG.

  In FIG. 10, when the receiving side VoIP communication apparatus 101 detects an improvement in reception quality monitored by itself (step 1000), it transmits a switchback request frame to the calling side VoIP communication apparatus 100 (step 1000). 1001), triggering a switchback process to the IP call.

  It waits for the next instruction based on the judgment of the originating VoIP communication apparatus 100 (step 1002). When the notification transmitted from the VoIP communication device 100 on the calling side is a switchback notification frame (step 1003: YES), switchback processing is performed, and as described with reference to FIG. The switch-back preparation response frame is transmitted to the originating VoIP communication device 100 (step 1004).

  Then, after a switchback notification response frame is transmitted, the line switching unit 304 switches back to the IP call after a certain timing, and when the disconnection of the PSTN call is detected, the PSTN line is blocked (step 1005). The above operation corresponds to the processing of FIG.

  On the other hand, if the notification transmitted from the originating VoIP communication device 100 is a switchback hold notification frame (step 1003: NO), the switchback processing is suspended and a switchback notification is sent from the calling VoIP communication device 100. Wait for the frame to be sent (step 1006). While the switch-back process is pending, it is monitored that the reception quality in the own apparatus is kept good (step 1007).

  When a switchback notification frame is sent from the calling-side VoIP communication apparatus 100 (step 1006: YES), the process returns to step 1004 to restart the switchback process. The above operation corresponds to the processing in FIG.

  If reception quality deterioration is detected in the own device while the switchback processing is pending (step 1007: NO), a communication quality deterioration report frame is transmitted to the originating VoIP communication device 100 to stop the switchback processing. (Step 1008). Each of the VoIP communication devices 100 and 101 stops the switch-back process by transmitting / receiving the communication quality degradation report frame. This operation corresponds to the processing in FIG.

  Next, with reference to FIGS. 11 to 13, a description will be given of a switch-back operation when a call is switched to the PSTN 104 due to the communication side 100 detecting a deterioration in communication quality. FIG. 11 shows three operations (a) to (c).

  Steps 1100 and 1101 in FIG. 11A show a PSTN call after switching from an IP call to a PSTN call by the above-described operation and IP communication performed for the purpose of monitoring the communication quality of the IP network 105. Yes. In such a state, it is assumed that the communication quality improvement of the IP network 105 is detected in the VoIP communication device 100 on the transmission side that has been monitoring the communication quality (step 1102). In other words, in this case, the call is switched to the PSTN 104 mainly by the calling-side VoIP communication apparatus 100, so that the calling-side VoIP communication apparatus 100 triggers a switchback.

  The VoIP communication apparatus 100 on the transmission side includes a control IP frame (switchback notification frame) including information for notifying that the currently connected PSTN call is switched back to the IP call as the communication quality of the IP network 105 is improved. Is sent to the VoIP communication apparatus 101 on the called side (step 1103) to instruct to prepare for processing to switch back to the IP call.

  The VoIP communication apparatus 101 on the receiving side that has received the switchback notification frame confirms that there is no detection of deterioration in the communication quality monitored by itself, and prepares for processing to switch back to the IP call (step 1104). . Then, a control IP frame (switchback notification response frame) for notifying that preparation has been completed is transmitted to the VoIP communication apparatus 100 on the transmission side (step 1105). Since the processing preparation for switching back to the IP call is as described above, a description thereof will be omitted.

  In addition, the originating side VoIP communication apparatus 100 that has received the switchback notification response frame performs switchback processing to the IP call (step 1106), the IP call is resumed (step 1107), and the PSTN call is disconnected. (Step 1108) The processing is the same as that described with reference to FIG.

  FIGS. 11B and 11C correspond to FIGS. 8B and 8C, respectively.

  FIG. 11B illustrates a case where reception quality degradation is detected in the incoming VoIP communication apparatus 101 when a return notification frame is received from the originating VoIP communication apparatus 100 that has triggered the switchback ( Step 1120). In this case, a switchback hold request frame is transmitted from the VoIP communication apparatus 101 on the receiving side to the VoIP communication apparatus 100 on the caller side (step 1121), and the switchback process is temporarily held until the reception quality at the own apparatus is improved. Request. When the reception quality at the own device is improved (step 1122), a switchback request frame is transmitted from the VoIP communication device 101 on the receiving side to the VoIP communication device 100 on the calling side (step 1123) to restart the switchback process.

  FIG. 11C shows a trigger for switching back while the VoIP communication device 101 on the receiving side that has detected the deterioration of the reception quality and requested temporary hold of the switch back processing is waiting for the reception quality improvement in its own device. By detecting the communication quality degradation in the originating VoIP communication apparatus 100 that has applied (step 1130), the originating VoIP communication apparatus 100 transmits a communication quality degradation report frame (step 1131), and the terminating VoIP communication apparatus This is a process of notifying the suspension of the switchback process to 101.

  The operation of the originating side VoIP communication apparatus 100 in the switchback processing when the call is switched to the PSTN 104 due to the fact that the originating side VoIP communication apparatus 100 has detected the deterioration of the communication quality described in FIG. The operation of the VoIP communication apparatus 101 on the side is shown in FIGS.

  FIG. 12 is a flowchart showing the operation of the originating VoIP communication apparatus 100 in the switch-back process described with reference to FIG. FIG. 13 is a flowchart showing the operation of the incoming side VoIP communication apparatus 101 in the switch-back processing described with reference to FIG.

  In FIG. 12, the VoIP communication device 100 on the transmission side that has detected an improvement in communication quality (step 1200) transmits a switchback notification frame to the VoIP communication device 101 on the reception side (step 1201), and the PSTN call is changed to an IP call. Notification of switching back to.

  Waiting for a response from the VoIP communication apparatus 101 on the called side (step 1202), upon receiving a switchback notification response frame that is a notification of completion of preparation for switching back to the IP call in the VoIP communication apparatus 101 on the called side (step 1203) Then, switching back to the IP call is performed (step 1204).

  If the response from the VoIP communication apparatus 101 on the incoming side is a switchback hold request frame, reception of a switchback request frame from the VoIP communication apparatus 101 on the incoming side is awaited. While waiting for reception of the switchback request frame from the VoIP communication apparatus 101 on the receiving side, the reception quality in the own apparatus is monitored (step 1205).

  When a switchback request frame is received from the incoming-side VoIP communication apparatus 101 (step 1205: YES), the subsequent processing is the same as step 900 in FIG.

  Further, when it is detected that the reception quality of the own device is deteriorated while waiting for the reception of the switchback request frame from the VoIP communication device 101 on the receiving side (step 1205: NO), it notifies that the switchback processing is stopped. The communication quality degradation report frame is transmitted to the VoIP communication apparatus 101 on the receiving side (step 1207), and the process is terminated.

  In FIG. 13, when the receiving side VoIP communication apparatus 101 that has received the switchback notification frame from the calling side VoIP communication apparatus 100 (step 1300) has good reception quality in its own apparatus (step 1301: YES), Returning the switchback notification response frame (step 1302), and performing switchback related processing (step 1303) to the IP call.

  In addition, when the reception side VoIP communication device 101 detects deterioration in the reception quality monitoring in its own device (step 1301: NO), the incoming side VoIP communication device 101 switches to request the suspension of the return processing to the originating side VoIP communication device 100. A return hold request frame is transmitted (step 1304). Then, the reception quality of the own device is monitored for improvement (step 1305).

  When the reception quality of the own device is improved (step 1305: YES), the incoming side VoIP communication device 101 proceeds to the processing of step 1001 in FIG. 10 and sends a switchback request frame to the outgoing side VoIP communication device 100. Send. The subsequent operation is the same as in FIG.

  If the communication quality deterioration report frame is received from the VoIP communication device 100 on the transmission side while monitoring the improvement of the reception quality of the own device (step 1306: YES), the processing is terminated.

  As described above, the communication system of the present invention holds the IP telephone communication path as it is even after the transition to the PSTN call, and transmits and receives an IP frame including a voice packet in a pseudo manner on the IP telephone communication path. Thus, the communication quality of the IP network 105 is constantly monitored. When the recovery of the communication quality of the IP network 105 is detected by this constant monitoring, the PSTN call can be switched to the IP call again after confirming the communication quality of both transmission and reception. For this reason, it is possible to make the best use of economical IP telephone communication, and it is possible to realize an optimal communication system in terms of both quality priority and economy.

  In the above-described embodiment, the VoIP communication device has been described as a device separate from the analog telephone connected thereto. However, the VoIP communication function and the analog telephone function are combined, and an IP network interface unit and a PSTN interface unit are provided. Needless to say, the present invention is also applied to an IP telephone having the same.

FIG. 1 is a system configuration diagram showing an embodiment of a communication system according to the present invention. FIG. 2 is a block configuration diagram showing a device configuration of the calling-side VoIP communication device. FIG. 3 is a block diagram showing the device configuration of the VoIP communication device on the receiving side. FIG. 4 is a sequence diagram illustrating an operation in which the incoming VoIP communication apparatus detects a deterioration in communication quality and requests the originating VoIP communication apparatus to switch the PSTN call. FIG. 5 is a sequence diagram illustrating an operation in which the originating VoIP communication apparatus detects a deterioration in communication quality and switches to a PSTN call. FIG. 6 is a schematic diagram conceptually showing how each VoIP communication apparatus notifies the IP telephone number and the PSTN telephone number to each other using the control IP frame and stores them in the address storage unit. . FIG. 7 is a block diagram conceptually showing the circuit configuration of the line switching unit. FIG. 8 is a sequence diagram showing an operation for switching back to an IP call when the call is switched to PSTN based on a request to switch the incoming VoIP communication apparatus. FIG. 9 is a flowchart showing the operation of the calling-side VoIP communication apparatus in the switch-back process described with reference to FIG. FIG. 10 is a flowchart showing the operation of the called-side VoIP communication apparatus in the switch-back process described with reference to FIG. FIG. 11 is a sequence diagram showing an operation for switching back to an IP call when the call is switched to PSTN due to the VoIP communication device on the caller side detecting deterioration in communication quality. FIG. 12 is a flowchart showing the operation of the calling-side VoIP communication apparatus in the switch-back process described with reference to FIG. FIG. 13 is a flowchart showing the operation of the VoIP communication apparatus on the receiving side in the switch-back process described with reference to FIG.

Explanation of symbols

100, 101 VoIP communication device 102 PSTN line 103 IP line 104 PSTN
105 IP network 106, 107 IP telephone 200, 300 Telephone interface unit 201, 301 PSTN interface unit 202, 302 WAN interface unit 203, 303 LAN interface unit 204, 304 Line switching unit 205, 305 PSTN peripheral circuit unit 206, 306 VoIP peripheral Circuit unit 207, 307 Address storage unit 208, 308 Main control unit 209, 309 Ethernet peripheral circuit unit 701 Branch circuit 702 Switching circuit 703 Pseudo-receiving circuit

Claims (33)

While performing an IP call using a VoIP communication apparatus that realizes voice communication via an IP (Internet Protocol) network by VoIP (Voice over Internet Protocol) communication by mutually converting an analog voice signal and a voice packet, the IP network The IP call is switched to a PSTN call that is a voice communication via a PSTN (Public Switched Telephone Network) due to the deterioration of the call quality of the IP call detected by monitoring the reception status of the IP frame arriving from In a communication system that continues communication,
The originating VoIP communication device that originated the IP call and the terminating VoIP communication device that received the IP call are:
During the IP call, a control IP frame including control information that can be transmitted / received between the outgoing and incoming VoIP communication devices is transmitted and received, and the operation control of the VoIP communication device of the own device is controlled by the control IP frame. Control unit that executes based on information and the telephone number for the IP call and the PSTN call that are transmitted to and received from the partner apparatus using the control IP frame and each VoIP communication apparatus Storage means for storing the telephone number for the IP call and the telephone number for the PSTN call of the counterpart apparatus received from the counterpart apparatus in association with the IP address of the counterpart apparatus, respectively.
Based on the control IP frame (switching request frame) including switching request information for instructing to switch the IP call to the PSTN call, transmitted by the VoIP communication device on the called side that detects the deterioration of the call quality, The calling-side VoIP communication device receives the telephone call via the PSTN using the PSTN call telephone number corresponding to the IP address of the called-side VoIP communication device stored in the storage means. A communication system characterized by making a call to the VoIP communication apparatus on the side. The originating VoIP communication device that has detected the deterioration of the call quality includes the control IP frame including switching notification information for notifying the terminating VoIP communication device to prepare for switching the IP call to the PSTN call. (Switch notification frame) is transmitted to the VoIP communication device on the called side, and the control IP including response information notifying that the preparation for switching the IP call to the PSTN call is completed from the VoIP communication device on the called side When a frame (switch notification response frame) is received, a telephone call via the PSTN is made using the PSTN call telephone number corresponding to the IP address of the called VoIP communication device stored in the storage means. 2. The communication system according to claim 1, wherein the call is transmitted to the VoIP communication apparatus on the receiving side. When the incoming VoIP communication apparatus detects an incoming telephone call via the PSTN, the incoming VoIP communication apparatus sends the control IP frame (acknowledgment completion notification frame) including information notifying that the incoming call has been accepted. A call circuit in the called VoIP communication device is switched from the IP call to the PSTN call after a predetermined timing after transmitting the reception completion notification frame.
3. The call origination VoIP communication device, when receiving the acceptance completion notification frame, switches the call circuit in the call origination VoIP communication device from the IP call to the PSTN call. Communication system. The incoming VoIP communication device transmits the PSTN telephone number corresponding to the IP address of the outgoing VoIP communication device stored in the storage means when a telephone call via the PSTN is received. The communication system according to any one of claims 1 to 3, wherein only the telephone call via the PSTN included in the user information is accepted. Each of the calling-side VoIP communication device and the called-side VoIP communication device monitors the transmission analog voice signal of a call that is continued by switching the IP phone to the PSTN call, and converts the voice signal. Switched IP network quality monitoring for transmitting and receiving IP frames including voice packets between the originating VoIP communication device and the terminating VoIP communication device via the IP network to monitor the communication quality of the IP network The communication system according to any one of claims 1 to 4, further comprising means. The terminating-side VoIP communication device performs the switching process for switching the IP phone to the PSTN call due to deterioration of call quality in the terminating-side VoIP communication device, and the terminating-side VoIP communication When the apparatus detects an improvement in the communication quality of the IP network, the control side IP frame (switchback request frame) including information for requesting execution of processing for switching the PSTN call back to the IP call is sent to the caller side. To the VoIP communication device of
The calling VoIP communication device is the case where the switching process is executed due to a deterioration in call quality in the calling VoIP communication device, and the calling VoIP communication device has a communication quality of the IP network. When an improvement is detected, the control IP frame (switchback notification frame) including information for notifying the VoIP communication apparatus on the receiving side to prepare for switching back the PSTN call to the IP call is sent to the receiving side. 6. The communication system according to claim 5, wherein the communication system transmits to a VoIP communication device. When the originating VoIP communication device receives the switchback request frame, the originating VoIP communication device confirms that no deterioration in communication quality of the IP network in the originating VoIP communication device has been detected, and sends the switchback notification frame The control IP frame (switchback notification) including response information transmitted to the callee VoIP communication device and informing the completion of preparation for switching the PSTN call back to the IP call from the callee VoIP communication device 7. The communication system according to claim 6, wherein when the response frame is received, the PSTN call is switched back to the IP call. When the originating VoIP communication apparatus receives the switchback request frame and detects a deterioration in communication quality of the IP network in the originating VoIP communication apparatus, the originating VoIP communication apparatus changes the PSTN call to the IP call. The control IP frame (switchback hold notification frame) including information for notifying that the switchback process is suspended is transmitted to the VoIP communication device on the called side, and then the VoIP communication device on the calling side transmits the IP network. 8. The communication system according to claim 7, wherein when the improvement in communication quality degradation is detected, the switchback notification frame is transmitted to the VoIP communication device on the receiving side. The caller VoIP communication device transmits the switchback hold notification frame to the callee VoIP communication device before transmitting the switchback notification frame to the callee VoIP communication device. The control IP frame (communication quality degradation) including information reporting the cancellation of the process of switching the PSTN call back to the IP call due to the VoIP communication apparatus of the IP network detecting the deterioration of the communication quality of the IP network. 9. The communication system according to claim 8, wherein when the report frame is received, the execution of the switch-back process is stopped. The originating VoIP communication device uses the switching notification frame transmitted by the originating VoIP communication device when the switching process is executed due to a deterioration in call quality in the originating VoIP communication device. On the other hand, upon receiving the switchback notification response frame transmitted after confirming that the incoming VoIP communication device has not detected the deterioration of the communication quality of the IP network in the incoming VoIP communication device, The communication system according to claim 6, wherein a process of switching the PSTN call back to the IP call is executed. The caller VoIP communication device transmits the PSTN call to the IP call when the callee VoIP communication device detects a deterioration in communication quality of the IP network in response to the switchback notification frame. When the control IP frame (switchback hold request frame) including information requesting to hold back the switchback process is received, the switchback process is held, and then the VoIP communication apparatus on the receiving side receives the IP network. 11. The communication system according to claim 10, wherein upon receiving the switch-back request frame that is detected and transmitted by detecting an improvement in communication quality degradation, a process of switching the PSTN call back to the IP call is executed. The caller VoIP communication device receives the switchback hold request frame from the callee VoIP communication device and then receives the switchback request frame before the caller VoIP communication device receives the switchover request frame. The communication quality deterioration report frame is transmitted to the VoIP communication apparatus on the receiving side, when execution of the process of switching the PSTN call back to the IP call is stopped. 11. The communication system according to 11. An analog voice signal and a voice packet are interconverted to perform an IP call as a voice communication via an IP (Internet Protocol) network by VoIP (Voice over Internet Protocol) communication, and reception status of an IP frame reaching from the IP network In the VoIP communication apparatus that continues communication by switching the IP call to a PSTN call that is a voice communication via a PSTN (Public Switched Telephone Network) when the deterioration of the call quality of the IP call is detected.
During the IP call, the control IP frame including control information that can be transmitted and received with the VoIP communication device of the communication partner is transmitted and received, and the operation control of the VoIP communication device is controlled by the control information of the control IP frame. IP frame transmission / reception control means for control executed based on
The telephone number for the IP call and the telephone number for the PSTN call given to the VoIP communication apparatus of the call destination, received from the VoIP communication apparatus of the call destination using the control IP frame, An address storage means for storing the IP address of the counterpart VoIP communication device in association with each other;
Line switching means for performing switching control of the interface with the IP network and the interface with the PSTN,
In the case where the VoIP communication device that has detected the deterioration of the call quality is the VoIP communication device on the called side that has received the IP call,
The control IP frame transmission / reception control means of the terminating VoIP communication apparatus transmits the control IP frame (switch request frame) including switch request information for instructing to switch the IP call to the PSTN call. To the VoIP communication device of
When receiving the switching request frame, the control IP frame transmission / reception control means of the originating VoIP communication apparatus that has originated the IP telephone call receives the IP of the terminating VoIP communication apparatus stored in the address storage means. Using the PSTN call telephone number corresponding to the address, making a telephone call via the PSTN;
When the VoIP communication device that has detected the deterioration of the call quality is the VoIP communication device on the calling side,
The control IP frame transmission / reception control means of the originating VoIP communication device includes the control IP including switching notification information for notifying the terminating VoIP communication device to prepare for switching the IP call to the PSTN call. A frame (switch notification frame) is transmitted to the VoIP communication device on the called side, and the control-use information including response information notifying that preparation for switching the IP call to the PSTN call is completed from the VoIP communication device on the called side When receiving an IP frame (switching notification response frame), a call is made via the PSTN using the PSTN call telephone number corresponding to the IP address of the VoIP communication device on the called side stored in the address storage means. 1. A VoIP communication apparatus for transmitting a call. When the control IP frame transmission / reception control means of the incoming VoIP communication device detects an incoming call through the PSTN, the control IP frame (including the information notifying that the incoming call has been accepted) A reception completion notification frame) is transmitted to the originating VoIP communication device, and after a predetermined timing from the transmission of the reception completion notification frame, a call circuit in the line switching means of the incoming VoIP communication device is Switch from IP call to PSTN call,
14. The call origination VoIP communication device, upon receiving the acceptance completion notification frame, switches the call circuit in the line switching means of the call origination VoIP communication device from the IP call to the PSTN call. VoIP communication apparatus of description. When the IP call is switched to the PSTN call and the communication is continued, the VoIP communication apparatus receives the telephone call via the PSTN and receives the call partner's VoIP communication apparatus stored in the address storage means 15. A PSTN line control means for accepting only a telephone call via the PSTN including caller information including a telephone number for the PSTN call corresponding to the IP address of the PSTN line. VoIP communication apparatus of description. The VoIP communication apparatus monitors a transmission analog voice signal of a call that is continued by switching the IP telephone to the PSTN call, and transmits an IP frame including a voice packet obtained by converting the voice signal via the IP network. Switched IP network quality monitoring for monitoring the communication quality of the IP network based on the reception status of the IP frame including the voice packet that has been transmitted from the VoIP communication device of the communication partner and arrived from the VoIP communication device of the communication partner 16. The VoIP communication apparatus according to claim 15, further comprising means. When the switching from the IP call to the PSTN call is performed due to the detection of the deterioration of the call quality in the called VoIP communication apparatus, the post-switching IP network quality monitoring of the called VoIP communication apparatus When the means detects an improvement in the communication quality of the IP network,
The control IP frame transmission / reception control means of the terminating VoIP communication device comprises:
Transmitting the control IP frame (switchback request frame) including information for requesting execution of processing for switching back the PSTN call to the IP call to the VoIP communication device on the caller side;
The PSTN transmitted by the originating VoIP communication device is confirmed by confirming that the IPTN communication quality monitoring means during the PSTN call of the originating VoIP communication device has not detected the deterioration of the communication quality of the IP network. When receiving the control IP frame (switchback notification frame) including information for notifying preparation for switching back a call to the IP call, it informs that preparation for switching back the PSTN call to the IP call has been completed. While transmitting the control IP frame (switchback notification response frame) including response information to the VoIP communication device on the caller side,
Switch back the call circuit in the line switching means from the PSTN call to the IP call after a predetermined timing from the transmission of the switchback notification response frame,
The control IP frame transmission / reception control means of the calling-side VoIP communication device comprises:
5. The PSTN call is disconnected when the switch-back notification response frame is received from the terminating VoIP communication device, and the call circuit in the line switching unit is switched back from the PSTN call to the IP call. 16. The VoIP communication device according to 16. The control IP frame transmission / reception control means of the terminating VoIP communication device transmits the switchback request frame to the originating VoIP communication device, and then the switched IP network quality of the originating VoIP communication device When the monitoring means detects deterioration of the communication quality of the IP network, the VoIP communication device on the transmission side transmits information for notifying that the process of switching the PSTN call back to the IP call is suspended. 18. The VoIP communication apparatus according to claim 17, wherein upon receiving an IP frame (switchback hold notification frame), the process is held until the switchback notification frame is received from the originating VoIP communication apparatus. The control IP frame transmission / reception control unit of the incoming VoIP communication device receives the incoming call after receiving the return hold notification frame from the outgoing VoIP communication device and before receiving the return notification frame. Control IP frame including information for reporting the suspension of the process of switching the PSTN call back to the IP call when the post-switching IP network quality monitoring means of the VoIP communication apparatus on the side detects the deterioration of the communication quality of the IP network 19. The VoIP communication apparatus according to claim 18, wherein a (communication quality degradation report frame) is transmitted to the originating VoIP communication apparatus, and the switch-back process is stopped. In the case where switching from the IP call to the PSTN call is performed due to the detection of deterioration of the call quality in the caller VoIP communication device, the post-switching IP network quality monitoring of the caller VoIP communication device When the means detects an improvement in the communication quality of the IP network,
The control IP frame transmission / reception control means of the calling-side VoIP communication device comprises:
Sending the switchback notification frame to the terminating VoIP communication device;
The switching back, wherein the terminating VoIP communication apparatus transmits after confirming that the IP network quality monitoring means after the switching of the terminating VoIP communication apparatus has not detected the degradation of the communication quality of the IP network. When the notification response frame is received, the PSTN call is disconnected, and the call circuit in the line switching unit is switched back from the PSTN call to the IP call.
The control IP frame transmission / reception control means of the terminating VoIP communication device comprises:
17. The VoIP communication apparatus according to claim 16, wherein the communication circuit in the line switching unit is switched back from the PSTN call to the IP call after a predetermined timing from the transmission of the switchback notification response frame. The control IP frame transmission / reception control means of the originating VoIP communication device transmits the switchback notification frame to the terminating VoIP communication device, and then the switched IP network quality of the terminating VoIP communication device The control including information for notifying the suspension of the process of switching the PSTN call back to the IP call, which is transmitted by the terminating VoIP communication apparatus when the monitoring unit detects a deterioration in communication quality of the IP network. 21. The VoIP communication apparatus according to claim 20, wherein when receiving the IP frame for use (switchback hold request frame), the process is held until the switchback notification response frame is received from the VoIP communication apparatus on the receiving side. The control IP frame transmission / reception control unit of the originating VoIP communication device receives the switchback hold request frame from the callee VoIP communication device and then receives the switchback notification response frame before receiving the switchback notification response frame. When the post-switching IP network quality monitoring means of the originating VoIP communication device detects the degradation of the communication quality of the IP network, the communication quality degradation report frame is transmitted to the terminating VoIP communication device, and the switchback processing is performed. The VoIP communication apparatus according to claim 21, wherein the VoIP communication apparatus is stopped. While performing an IP call using a VoIP communication apparatus that realizes voice communication via an IP (Internet Protocol) network by VoIP (Voice over Internet Protocol) communication by mutually converting an analog voice signal and a voice packet, the IP network The IP call is switched to a PSTN call that is a voice communication via a PSTN (Public Switched Telephone Network) due to the deterioration of the call quality of the IP call detected by monitoring the reception status of the IP frame arriving from In a communication method for continuing communication,
Each of the originating VoIP communication device that originated the IP call and the terminating VoIP communication device that received the IP call is between the originating and terminating VoIP communication devices during the IP call. Using the control IP frame including control information that can be transmitted and received, the telephone number for the IP call and the telephone number for the PSTN call given to each of the VoIP communication devices are respectively transmitted to the other device,
The telephone number for the IP call and the telephone number for the PSTN call received from the partner apparatus are stored in correspondence with the IP address of the partner apparatus,
When the called VoIP communication apparatus detects a deterioration in call quality during the IP call,
The terminating VoIP communication device transmits the control IP frame (switching request frame) including switching request information instructing to switch the IP call to the PSTN call to the originating VoIP communication device,
When the calling side VoIP communication apparatus receives the switching request frame, the call via the PSTN is performed using the PSTN call telephone number corresponding to the stored IP address of the called VoIP communication apparatus. A communication method, comprising: transmitting a call from the originating VoIP communication device to the terminating VoIP communication device. When the VoIP communication device on the calling side detects the deterioration of the call quality during the IP call,
The calling VoIP communication device receives the control IP frame (switching notification frame) including switching notification information for notifying the receiving VoIP communication device to prepare for switching the IP call to the PSTN call. To the VoIP communication device on the side,
The incoming VoIP communication device transmits the control IP frame (switching notification response frame) including response information notifying that preparation for switching the IP call to the PSTN call is completed,
The calling VoIP communication device makes a telephone call via the PSTN using the PSTN call telephone number corresponding to the stored IP address of the called VoIP communication device. The communication method according to claim 23, wherein the communication is transmitted to the communication device. When a telephone call via the PSTN arrives, the called VoIP communication device
Accepting only telephone calls via the PSTN that include in the caller information the PSTN telephone number corresponding to the stored IP address of the calling VoIP communication device;
Transmitting the control IP frame (acknowledgment completion notification frame) including information for notifying that an incoming call is received via the PSTN to the VoIP communication device on the caller side;
After a predetermined timing after transmitting the acceptance completion notification frame, switching the IP call to the PSTN call in the VoIP communication device on the called side,
The communication method according to claim 23 or 24, wherein the originating VoIP communication device that has received the acceptance completion notification frame switches the IP call to the PSTN call in the originating VoIP communication device. . Each of the caller VoIP communication device and the callee VoIP communication device includes:
The transmission analog voice signal of the ongoing call is monitored by switching the IP telephone to the PSTN call, and an IP frame including a voice packet obtained by converting the voice signal is sent to the VoIP communication on the caller side via the IP network. The communication method according to any one of claims 23 to 25, wherein communication quality of the IP network after switching is monitored by transmitting and receiving between the device and the VoIP communication device on the receiving side. . When the IP telephone is switched to the PSTN call due to a deterioration in call quality in the called VoIP communication apparatus, and the called VoIP communication apparatus detects an improvement in the communication quality of the IP network The VoIP communication apparatus on the receiving side sends the control IP frame (switchback request frame) including information for requesting execution of processing for switching the PSTN call back to the IP call to the VoIP communication apparatus on the calling side. Send
When the IP telephone is switched to the PSTN call due to the deterioration of the call quality in the caller VoIP communication device, and the caller VoIP communication device detects an improvement in the communication quality of the IP network Includes a control IP frame (switchback notification frame) including information for notifying the callee VoIP communication device so that the calling VoIP communication device prepares to switch back the PSTN call to the IP call. 27. The communication method according to claim 26, wherein the communication is transmitted to the VoIP communication device on the called side. When the IP telephone is switched to the PSTN call due to a deterioration in call quality in the called VoIP communication apparatus, and the called VoIP communication apparatus detects an improvement in the communication quality of the IP network When the originating VoIP communication device receives the switchback request frame transmitted by the terminating VoIP communication device,
The originating VoIP communication device transmits the switchback notification frame to the terminating VoIP communication device after confirming that the communication quality of the IP network has not deteriorated,
The control IP frame (switchback notification response frame) including response information indicating that the receiving side VoIP communication apparatus that has received the switchback notification frame has completed preparation for switching back the PSTN call to the IP call. Send
28. The communication method according to claim 27, wherein when the originating VoIP communication apparatus receives the switchback notification response frame, the PSTN call is switched back to the IP call. When the call-back request frame is received and the originating VoIP communication device detects a deterioration in communication quality of the IP network,
The originating VoIP communication device sends a control IP frame (switchback hold notification frame) including information notifying that the process of switching back the PSTN call to the IP call to the IP call to the receiving VoIP communication device. Send
29. The switchback notification frame is then transmitted to the terminating VoIP communication device when the originating VoIP communication device detects improvement in communication quality degradation of the IP network. The communication method described. After the originating VoIP communication device transmits the switch-back hold notification frame to the called VoIP communication device and before transmitting the switch-back notification frame, the called-side VoIP communication device is connected to the IP network. If we detect degradation in communication quality,
The terminating VoIP communication apparatus transmits the control IP frame (communication quality degradation report frame) including information for reporting the cancellation of the process of switching the PSTN call back to the IP call and stops the switch-back process. And
30. The communication method according to claim 29, wherein the originating VoIP communication apparatus receives the communication quality degradation report frame and stops the switch-back process. When the IP telephone is switched to the PSTN call due to the deterioration of the call quality in the caller VoIP communication device, and the caller VoIP communication device detects an improvement in the communication quality of the IP network When the incoming VoIP communication device receives the switchback notification frame transmitted by the outgoing VoIP communication device,
The control IP including response information that informs that the terminating VoIP communication apparatus is ready to switch the PSTN call back to the IP call after confirming that the communication quality of the IP network has not deteriorated Send a frame (switchback notification response frame)
28. The communication method according to claim 27, wherein when the originating VoIP communication apparatus receives the switchback notification response frame, the PSTN call is switched back to the IP call. When the incoming VoIP communication apparatus detects a deterioration in communication quality of the IP network when receiving the switchback notification frame,
The incoming VoIP communication apparatus transmits the control IP frame (switchback hold request frame) including information for notifying that the incoming VoIP communication apparatus holds the process of switching back the PSTN call to the IP call. To
32. The switchback request frame is then transmitted to the caller VoIP communication device when the callee VoIP communication device detects improvement in communication quality deterioration of the IP network. The communication method described. After the terminating VoIP communication device has transmitted the switchback hold request frame to the originating VoIP communication device and before transmitting the switchback request frame, the originating VoIP communication device is connected to the IP network. If a degradation in communication quality is detected,
The originating VoIP communication device transmits the communication quality degradation report frame and stops the switchback process,
The communication method according to claim 32, wherein the terminating VoIP communication apparatus receives the communication quality degradation report frame and stops the switch-back process.

Images