JP2008219440A - Radio ip telephone set and radio ip telephone set system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio IP telephone set and a radio IP telephone set system constituted in such a manner that normal call incoming processing and telephone call processing can be performed in an IP telephone system where a radio IP telephone whose radio wave intensity is not sufficient is present. <P>SOLUTION: This radio IP telephone set has a decision unit which decides whether radio wave intensity is lower than a predetermined value. When the notice of incoming call detection is sent from a call control server, a telephone number decision unit decides whether an incoming call destination telephone number included in the notice of incoming call detection is a group telephone number. When it is decided that the incoming call destination telephone number is the group telephone number, an incoming call reception/rejection decision unit confirms the radio wave intensity using the decision unit. When the radio wave intensity is lower than the predetermined value, an incoming call reception/rejection determination unit sends a signal indicating the rejection of an incoming call, e.g. a busy-tone signal back to the call control server. Consequently, processing after incoming call detection, for example, the ringing of a ringtone is not performed by a radio IP telephone set whose radio wave intensity is low. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless IP (Internet Protocol) telephone connected to a telephone line provided by a communication company such as NTT, and in particular, has a group telephone function for sharing one or a plurality of telephone numbers among a plurality of wireless IP telephones. The present invention relates to a provided wireless IP telephone and a wireless IP telephone system.

  In recent years, with the development of communication infrastructure, various additional services related to communication have become widespread. In particular, for telephones, IP telephone systems that provide various services by a call control server performing communication control of a plurality of IP telephones in an IP telephone network or a LAN (Local Area Network) are widely used.

  As one of the systems included in the IP telephone system, there is a group telephone system. The group telephone system is a system that manages a plurality of IP telephones in one or a plurality of groups and performs call control in units of groups. Thereby, for example, one telephone number can be shared by a plurality of IP telephones included in the same group. Hereinafter, a telephone number assigned to one group in the group telephone system is referred to as a “group telephone number”.

  Next, a method for receiving a group telephone number will be described. The group telephone number reception method includes a simultaneous reception method, a sequential search method, and a round robin method. The simultaneous incoming call method is a method in which all IP telephones belonging to the same group receive incoming calls simultaneously. According to this method, when an incoming call is made to a group telephone number, all the IP telephones belonging to the same group receive the call at the same time, and a call is made with any one of the IP telephones that responded first.

  On the other hand, the sequential search method and the round robin method are methods for receiving a call from any one IP telephone selected by the call control server according to a predetermined selection order. In the sequential search method, a selection order is assigned in advance to each IP telephone belonging to a group. Then, when an incoming call to the group telephone number occurs, the incoming call is made to any one of the telephones selected by the call control server according to the selection order. In this method, a telephone having a higher selection order receives the highest priority, and the number of incoming calls is the highest.

  The round robin method is a method in which a telephone set belonging to a group does not have a selection order. When an incoming call for a group telephone number occurs, the call control server shifts the selection order of subordinate IP telephones for each incoming call. As a result, incoming calls can be uniformly allocated to all IP telephones managed by the call control server.

  In the sequential search method and the round robin method, when a busy signal is returned from the IP telephone selected by the call control server, the call control server shifts the incoming call to the IP telephone of the next selection order. Note that some of the names and operations of the above-described incoming call methods may differ depending on the telecommunications carrier providing the service.

  In the incoming call control method using the group telephone number as described above, a plurality of wireless IP telephones existing in the group are not always in the same state when an incoming call occurs. Specifically, there is a case where a specific wireless IP telephone cannot receive a call due to a battery shortage state or a radio wave strength shortage state. Alternatively, even if an incoming call is possible, there is a possibility that the communication function will be lost due to the above factors after the start of the call. However, the call control server performs incoming call control without being aware of the state of each wireless IP telephone when an incoming call is received for the group telephone number.

  For this reason, for example, a user uses a wireless IP phone with insufficient battery or insufficient radio wave strength for response, and as a result, abnormal operation or communication malfunction after starting a call, for example, a part of the call voice cannot be heard. Could cause.

  In relation to the above, Patent Document 1 discloses a mobile phone that can receive as many calls from important callers as possible when the remaining power of a storage battery (= battery) is reduced. The mobile phone of Patent Document 1 includes an input means for allowing a user to input an important caller telephone number. The input important caller telephone number is stored in the memory. When it is detected that the remaining power of the storage battery has fallen below a predetermined level and a call is made to the local station from the outside, it is determined whether or not the caller's telephone number is registered in the memory. .

As a result of the determination, the incoming call processing is performed only when the caller's telephone number is registered in the memory, and when it is not registered, the incoming call processing is not performed. According to the mobile phone of Patent Document 1 as described above, it is possible to receive as many calls from important callers as possible when the remaining power of the storage battery is reduced.
JP 2000-278754 A

However, the mobile phone disclosed in Patent Document 1 has a problem in that calls made by the user are restricted because the incoming call is restricted by the telephone number of the caller when the remaining battery level is low. Also, there is no disclosure of countermeasures such as making a call using another alternative device for an incoming call that could not be made due to restrictions. In addition, no countermeasure is disclosed for a case where a communication failure occurs due to insufficient radio field intensity.

  The present invention has been made in order to solve the above-described problem, and an object of the present invention is to provide a wireless IP telephone used in an IP telephone system using a call control server. An object of the present invention is to provide a wireless IP telephone that can perform normal incoming call processing and call processing even in a case where a sufficient communication function cannot be maintained.

  In order to achieve the above object, the wireless IP telephone of the present invention associates wireless communication means connectable to a wireless communication network with a group telephone number, which is a telephone number that can be shared by a plurality of IP telephones, and an IP telephone. A server for recording received group management information, which receives an incoming call to the group telephone number, determines an IP telephone associated with the group telephone number using the group management information, and provides an incoming call detection notification Communication control means for communicating with the wireless communication means, and the radio communication means measures the radio field intensity of the radio wave received from the radio communication network, and the radio field intensity falls below a predetermined value. A radio IP telephone having a radio field strength judging means for judging whether or not the communication control means receives the incoming call detection notification from the call control server The telephone number determination means for determining whether the destination telephone number is the group telephone number, and when the telephone number determination means determines that the destination telephone number is the group telephone number. An incoming / outgoing determination unit that determines the radio field intensity using the radio field intensity determination unit, and the incoming / outgoing determination unit determines that the radio field intensity is below a predetermined value as a result of the determination of the radio field intensity. In this case, a signal indicating rejection of incoming calls is transmitted to the call control server using the communication control means.

  According to this configuration, the wireless IP telephone of the present invention includes the antenna device that can be connected to the wireless LAN. A communication control unit that communicates with the call control server using the antenna device is provided. In addition, a radio field intensity determination unit (= radio field intensity determination unit) that measures the radio field intensity of the radio wave received by the antenna device and determines whether the radio field intensity is below a predetermined value is provided.

  The wireless IP telephone set to which the incoming call detection notification is given from the call control server determines whether or not the destination telephone number is a group telephone number by the telephone number determination unit. If it is determined that the telephone number is a group telephone number, the incoming / outgoing possibility determining unit (= incoming / outgoing possibility determining means) checks the radio field intensity using the radio field intensity determining unit. If the field intensity is below a predetermined value, the incoming / outgoing determination unit returns a signal indicating rejection of the incoming call, such as a busy signal, to the control server. As a result, in a wireless IP telephone in which the antenna device is in a state where the radio field intensity is insufficient, processing after detection of an incoming call, for example, ringing of a ringing tone, is not performed.

  In order to achieve the above object, the wireless IP telephone according to the present invention, when the radio field intensity determining unit determines that the radio field intensity is lower than a predetermined value, from the group management information to the call control server. A deletion instructing unit for instructing to delete information relating to the wireless IP telephone; and when the radio field strength determining unit determines that the radio field intensity exceeds a predetermined value, the group management It is characterized by comprising registration instruction means for instructing to register information related to the wireless IP telephone in the information.

  According to this configuration, the radio field strength determination unit periodically confirms the radio field strength of the antenna device. When it is detected that the radio field intensity is lower than the predetermined value, the deletion instruction unit deletes information related to the wireless IP phone from the group management information recorded in the user information database to the call control server. To instruct. Upon receiving this, the call control server deletes the corresponding information from the user information database. For this reason, when an incoming call addressed to a group telephone number is detected, an incoming call detection notification is not transmitted to the wireless IP phone. Accordingly, the incoming call processing is not performed in the wireless IP phone.

Conversely, when it is detected that the radio field intensity exceeds a predetermined value, the registration instruction unit registers information regarding the wireless IP phone in the group management information recorded in the user information database with respect to the call control server. To instruct. Upon receiving this, the call control server registers the corresponding information in the user information database. Therefore, when an incoming call addressed to the group telephone number of the group to which the wireless IP phone belongs is detected, an incoming call detection notification is transmitted to the wireless IP phone as usual, and an incoming call process is performed.
The wireless IP telephone set according to claim 3 is characterized by rejecting an incoming call from the call control server when it is determined that the radio field intensity is below a predetermined value.
The wireless IP telephone set according to claim 4 transmits a busy signal to the call control server when it is determined that the radio field intensity is below a predetermined value.

  The wireless IP telephone system according to claim 5 is a system comprising at least first and second wireless IP telephones and a call control server, and the first IP telephone receives when there is an incoming call from an outside line. When the radio field intensity of the radio wave to be transmitted falls below a predetermined value, the call control server does not transmit a call signal to the first wireless IP telephone, but transmits a call signal to the second wireless IP telephone. .

  The wireless IP telephone system according to claim 6 is a system comprising at least first and second wireless IP telephones and a call control server, and the first IP telephone receives when there is an incoming call from an outside line. When the radio wave intensity of the radio wave to be transmitted falls below a predetermined value, the first IP telephone transmits a signal indicating that the radio wave intensity of the radio wave received by the first IP telephone is below a predetermined value to the call control server. When the call control server receives the signal, the call control server does not transmit a call signal to the first IP telephone, but transmits a call signal to the second IP telephone.

  The wireless IP telephone system according to claim 7 is a system composed of at least first and second wireless IP telephones and a call control server, and is received by the first IP telephone when there is an incoming call from an outside line. When the radio field intensity of the radio wave to be transmitted falls below a predetermined value, the first IP telephone transmits a busy signal to the call control server, and when the call control server receives the signal, the first IP telephone calls the first IP telephone. A call signal is transmitted to the second IP telephone without transmitting a signal.

According to the configuration of the present invention, when the wireless IP telephone receives an incoming call detection notification from the call control server, it is determined whether or not the incoming telephone number is a group telephone number. And when it is a group telephone number, the radio field strength is checked by the radio field strength judging unit. If the radio wave intensity is below a predetermined value, the incoming call permission / rejection determination unit returns a signal indicating call rejection to the call control server. As a result, in the wireless IP telephone in a state where the radio field intensity is insufficient, processing after detection of an incoming call, for example, ringing of a ringtone is not performed.

  For this reason, the incoming call response by the wireless IP telephone whose communication state is unstable due to insufficient radio wave intensity can be prohibited. As a result, for example, problems that may occur when a user responds with a radio IP phone with insufficient radio field strength, such as voice quality degradation and unexpected abnormal operation due to insufficient radio field strength, are avoided in advance. Is possible.

  Further, according to the configuration of the present invention, when the radio field intensity of the antenna device is confirmed and it is detected that the radio field intensity is below a predetermined value, the information regarding the wireless IP telephone is transmitted to the call control server as group management information. To remove it from For this reason, even if an incoming call addressed to the group telephone number of the group to which the wireless IP telephone belongs is detected in the call control server, the incoming call detection notification is not transmitted to the wireless IP telephone, and the incoming call detection is detected. No further processing is performed.

  For this reason, the incoming call response by the wireless IP telephone whose communication state is unstable due to insufficient radio wave intensity can be prohibited. As a result, for example, problems that may occur when a user responds with a radio IP phone with insufficient radio field strength, such as voice quality degradation and unexpected abnormal operation due to insufficient radio field strength, are avoided in advance. Is possible. Further, it is possible to prevent the call control server from repeatedly issuing a communication request to a wireless IP phone that does not reach the communication request due to insufficient radio wave intensity. For this reason, useless communication processing does not occur.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, embodiment shown here is an example and this invention is not limited to embodiment shown here.

[Embodiment 1]
<1-1. IP phone system configuration>
FIG. 1 is a block diagram showing a configuration of an IP telephone system including a wireless IP telephone 10 (= wireless IP telephone 10a to wireless IP telephone 10c in the figure) according to the present invention. The IP telephone system includes at least the wireless IP telephone 10, call control server 30, wired LAN 41, wireless LAN 42 (= wireless communication network), router 51, wireless LAN access point 52, gateway 53, IP telephone network 61, PSTN network 62 (= It is configured to include a public switched telephone network, a subscriber telephone 71, and a fixed IP telephone 80 (= fixed IP telephone 80a to fixed IP telephone 80c in the figure).

  The wireless IP telephone 10 is a wireless telephone for performing voice communication with other telephones via the IP telephone network 61 and the PSTN network 62 by being connected to a wireless LAN 42 described later and communicating with a wireless LAN access point 52. is there. Details of the wireless IP telephone 10 will be described later.

  The call control server 30 is a communication control device that performs communication control of a client (for example, the wireless IP telephone 10) using, for example, SIP (Session Initiation Protocol). Note that SIP is a kind of call control protocol having a transfer function, a caller ID notification function, and the like, and has a feature that it takes less time to connect than a protocol of the same system. The call control server 30 has functions such as a register server in which a client registers an address, a proxy server that searches for an address on behalf of the client, and a redirect server that transfers a connection request received from the client to another address.

  With the above function, the call control server 30 can perform outgoing call processing, incoming call processing, call processing, and the like between clients. Communication between the client and an external telephone (for example, subscriber telephone 71) can also be performed. The call control server is provided with a user information database 31 (= group management information). In the user information database 31, information on clients managed by the call control server 30, for example, information indicating the MAC addresses of the clients and the presence / absence of a personal telephone number assigned to each client is recorded.

  The wired LAN 41 is a local network in which the call control server 30, the router 51, the fixed IP telephone 80, and the like are connected by wire. Each of the above devices can communicate with each other by being connected to the wired LAN 41. Examples of physical means for connecting the devices constituting the wired LAN 41 include 10BASE-T (standardized as IEEE802.3i) and 100BASE-TX (standardized as IEEE802.3u) using a twisted pair cable. .

  The wireless LAN 42 is a local network in which the wireless IP telephone 10 and a wireless LAN access point are wirelessly connected. Each of the above devices can communicate with each other by being connected to the wireless LAN 42. As a physical means for connecting the devices constituting the wireless LAN 42, for example, a wireless communication method such as IEEE 802.11b standard or IEEE 802.11g standard using a radio wave with a frequency of 2.4 GHz can be used. is there.

  The router 51 is a network relay device for interconnecting a plurality of IP networks. Specifically, the transfer is performed by analyzing a part of the protocol of the network layer (third layer) and the transport layer (fourth layer) in the OSI (Open Systems Interconnection) reference model. In the present embodiment, it has a role of interconnecting two IP networks, a wired LAN 41 and an IP telephone network 61.

  The wireless LAN access point 52 is a radio wave relay that connects terminals (for example, the wireless IP telephone 10) in the wireless LAN 42. The wireless LAN access point 52 also has a function of connecting the wired LAN 41 and the wireless LAN 42. The wireless LAN access point 52 is roughly classified into two types, a bridge type and a router type. The former is a device that simply relays data transfer. The latter is a device having a routing function, a NAT function, and the like, and has a function of connecting a plurality of different IP networks.

  The gateway 53 is a protocol converter for interconnecting networks having different protocol systems. For example, the gateway 53 connects an IP network (for example, a wired LAN 41) and the PSTN network 62, and performs signal conversion using a signaling protocol such as SIP, thereby enabling communication between both networks.

  The IP telephone network 61 is a communication network using VoIP (Voice over Internet Protocol) technology for part or all of the telephone network, and FTTH (Fiber To The Home) and ADSL (Asymmetric Digital Subscriber) are used as communication lines. So-called broadband lines are used. Note that VoIP is a technique in which voice is compressed by various encoding methods, converted into packets, and transmitted in real time over an IP network. As a result, the IP telephone network 61 can provide a videophone service for transmitting and receiving images in addition to a voice call service.

  The PSTN network 62 is a general subscriber telephone line network. It is used to make a voice call by connecting a telephone device to the end and connecting to a communication partner by a circuit switching method. The subscriber telephone 71 is a telephone device that allows a telephone subscriber to make a voice call with another subscriber telephone or an IP telephone using the PSTN network 62.

  The fixed IP telephone 80 is an IP telephone that is connected to the wired LAN 41 by 10BASE-T or the like. The fixed IP telephone 80 has substantially the same configuration as that of the wireless IP telephone 10 except that the interface connected to the network is wired, and the details thereof are the same as those in the prior art. Is omitted.

<1-2. Internal configuration of wireless IP phone>
FIG. 2 is a block diagram showing the inside of the wireless IP telephone 10 according to the first embodiment of the present invention. The wireless IP telephone 10 includes at least a control unit 11, a memory 12, a display unit 13, an input unit 14, a communication control unit 15 (= communication control unit), a battery 16, a remaining capacity determination unit 17 (= remaining capacity determination unit), an antenna. A device 18 (= wireless communication means), an audio signal processing unit 19, a speaker 20, and a microphone 21 are included.

  The control unit 11 is a central processing unit for performing overall control of communication control processing (transmission / reception of voice data, execution of a call, detection of an incoming call, etc.) by controlling each unit of the wireless IP telephone 10. The control unit 11 includes a telephone number determination unit 11a (= phone number determination unit) and an incoming / outgoing possibility determination unit 11b (=) as functional units realized by executing a program on the arithmetic processing device included in the control unit 11. An incoming / outgoing determination unit).

  The telephone number determination unit 11a receives the incoming call detection notification from the call control server 30, and analyzes the incoming call number included in the incoming call detection notification. Then, it is determined whether the incoming call number is a group telephone number or a personal telephone number in which the telephone number and the IP telephone are associated one-to-one. The determination result is given to the incoming / outgoing determination unit 11b.

  Whether or not the incoming number is a group telephone number is determined by referring to telephone number information recorded in advance in the memory 12, for example. Or the flag information which shows whether it is the incoming call addressed to the group telephone number is included in the incoming call detection notification, and the form may be determined by referring to the flag information.

  The incoming / outgoing determination unit 11b receives an incoming detection notification from the call control server 30, and when the telephone number determination unit 11a determines that the incoming number is a group telephone number, the remaining capacity determination unit 17 (to be described later) 16 capacity determination processing is instructed. If the remaining capacity of the battery 16 is below a predetermined value as a result of the capacity determination process, a signal indicating call rejection is transmitted to the call control server using the communication control unit 15. As a signal used for call rejection, for example, a busy notification signal indicating that the wireless IP telephone 10 is busy is used.

  The memory 12 is a medium for temporarily storing various data held by the wireless IP telephone 10, and is configured by, for example, a writable RAM (Random Access Memory). The memory 12 serves as a buffer memory for temporarily storing processing data when various kinds of communication control processing are performed by the control unit 11, instruction commands received from the user, and the like.

  In the memory 12, for example, battery capacity information indicating the remaining battery capacity of the battery 16 to be described later, or indicating that the remaining battery capacity is lower than a predetermined value (= remaining capacity shortage state). A remaining capacity shortage flag or the like is recorded. The remaining capacity shortage flag is set to be effective when the remaining capacity confirmation unit 17 described later detects a shortage of the remaining capacity of the battery 16. Further, when the remaining capacity check unit 17 detects that the remaining capacity shortage has been resolved by charging the battery 16 or the like, it is set to invalid.

  The display unit 13 displays various information held by the wireless IP telephone 10 (for example, a calling party telephone number at the time of incoming call) to the user. The display unit 13 uses, for example, a small display device that consumes less power, such as a liquid crystal panel.

  The input unit 14 is used for a user to perform various operations (for example, input of a telephone number of a partner with whom a call is made) for performing communication using the wireless IP telephone 10. The input unit 14 is usually composed of a plurality of keys such as numeric keys and redial keys.

  The communication control unit 15 performs wireless communication in accordance with a communication standard (for example, IEEE 802.11b) using the wireless LAN 42 connected by the antenna device 18. As a result, the wireless IP telephone 10 can communicate with the wireless LAN access point 52 connected to the wireless LAN 42. Furthermore, by performing communication with the call control server 30 via the wireless LAN access point 52, it is possible to perform incoming call processing, outgoing call processing, and the like in the IP telephone system.

  The battery 16 is supplied with electric power from an external power source (not shown) and temporarily stores the electric power. For example, a rechargeable alkaline battery or a lithium ion battery is used. The remaining capacity determination unit 17 periodically checks the remaining capacity of the electric power stored in the battery 16. Then, it is determined whether or not the remaining capacity is lower than a predetermined value. As a standard for determining the predetermined value, it is desirable that the capacity is such that the wireless IP telephone 10 can perform a call function or a communication request transmission / reception function via the wireless LAN 42 without any trouble.

  The antenna device 18 transmits and receives radio communication radio waves to and from the wireless LAN access point 52. As a result, the wireless communication unit 16 and thus the wireless IP telephone 10 are connected to the wireless LAN 42.

  The audio signal processing unit 19 performs a decoding process on the audio data input by the communication control unit 15 and supplies it to the speaker 20 as an audio signal. The audio signal processing unit 19 performs a predetermined encoding process on the audio signal input from the microphone 21 to generate audio data, and supplies the audio data to the communication control unit 15. As a result, the audio data is transmitted to another telephone connected through the wired LAN 41, the wireless LAN 42, the IP telephone network 61, or the like.

  The speaker 20 converts the sound signal into sound and outputs the sound. For example, a voice signal including a call voice received from the fixed IP telephone 80 is converted into voice and output. When the speaker 20 outputs sound, the volume can be adjusted using a power amplifier (not shown). The microphone 21 inputs voice, converts it into a voice signal, and gives it to the voice signal processing unit 19. The audio signal given to the audio signal processing unit 19 is transmitted to other telephones via the communication control unit 15 and the antenna device 18.

<1-3. About incoming call control processing>
Here, the incoming call control processing of the wireless IP telephone 10 in the first embodiment of the present invention will be described with reference to the block diagrams of FIGS. 1 and 2 and the flowchart of FIG.

  The processing flow shown in FIG. 3 can be started at an arbitrary timing in a state where the power source of the wireless IP telephone 10 is activated and communication with the call control server 30 is possible. After the start of this process, in step S110, the control unit 11 determines whether or not the communication control unit 15 has received an incoming call detection notification from the call control server 30 via the wireless LAN.

  When it is determined that the incoming call detection notification has not been received, the process proceeds to step S110 again, and the detection process is repeatedly performed until the incoming call detection notification is detected. Conversely, if it is determined that the incoming call detection notification has been received, the telephone number determination unit 11a analyzes the incoming call number included in the incoming call detection notification in step S120. In the analysis, the telephone number information read from the memory 12 is referred to.

  Based on the result of the analysis in step S120, the telephone number determination unit 11a determines whether or not the incoming call number is a group telephone number in step S130. When it is determined that it is not a group telephone number, for example, when it is determined that it is a personal telephone number, the control unit 11 performs a normal incoming call process in step S151. Specifically, for example, a ringing tone is emitted from the speaker 20, an incoming call notification is displayed on the display unit 13, and the like. Thereafter, the process proceeds to step S110, where the incoming call detection process is performed again, and this process is continued.

  Conversely, when it is determined in step S130 that the incoming number is a group telephone number, the telephone number determination unit 11a gives the notification to the incoming / outgoing determination unit 11b. The incoming / outgoing possibility determination unit 11 b that has received the notification instructs the remaining capacity determination unit 17 to perform the remaining capacity determination process of the battery 16. Receiving the instruction, the remaining capacity determination unit 17 checks the remaining capacity of the battery 16 in step S140. Then, it is determined whether or not the remaining capacity obtained by the confirmation exceeds a predetermined value, and the determination result is given to the call acceptance / rejection determination unit 11b.

  The incoming / outgoing determination unit 11b given the determination result confirms the determination result of the remaining capacity in step S150. As a result of the confirmation, if the remaining capacity is not less than the predetermined value, the incoming call permission / non-permission determining unit 11b proceeds to the above-described step S151.

  On the other hand, if the remaining capacity is below the predetermined value in step S150, the incoming call availability determination unit 11b uses the communication control unit 15 to reject the incoming call to the call control server 30 in step S160. For example, a busy signal or the like is transmitted. Thereafter, the process proceeds to step S110, and this process is continued by entering the state of performing the incoming call detection process again.

  This processing described above is normally terminated when the power of the wireless IP telephone 10 is stopped or when the battery runs out. However, it may be configured such that the processing can be interrupted at an arbitrary timing by providing an instruction receiving unit that receives a processing interruption instruction.

Next, a second embodiment of the present invention will be described with reference to the drawings.
[Embodiment 2]
<2-1. IP phone system configuration>
Since it is the same content as Embodiment 1, description is abbreviate | omitted here.

<2-2. Internal configuration of wireless IP phone>
FIG. 4 is a block diagram showing the inside of the wireless IP telephone 10 according to the second embodiment of the present invention. In addition, about the apparatus part of the same content as Embodiment 1, description shall be abbreviate | omitted by adding the same code | symbol. As a configuration different from the first embodiment, the control unit 11 includes a deletion instruction unit 11c (= deletion instruction unit) and a registration instruction unit 11d (= registration instruction unit).

  When the remaining capacity determination unit 17 performs the capacity determination process of the battery 16 as a result of the remaining capacity determination unit 17 performing the capacity determination process, the deletion instruction unit 11c notifies the call control server 30 of the user. Send registration deletion signal. Specifically, for example, a REGISTER signal in which 0 is specified in the Expires header is transmitted using the communication control unit 15. As a result, the user registration of the wireless IP telephone 10 is deleted. By this processing, the registration information of the wireless IP phone 10 is invalidated, and thereafter, the wireless IP phone 10 becomes unusable on the IP phone system. In this state, when there is an incoming call addressed to the corresponding wireless IP telephone set 10, the call control server side performs a process of transferring the incoming call destination to another IP telephone set. For this reason, the incoming notification signal is not transmitted to the corresponding IP telephone.

  When the remaining capacity determination unit 17 performs the capacity determination process of the battery 16 and the remaining capacity of the battery 16 exceeds a predetermined value, the registration instruction unit 11d Send a registration signal. Specifically, for example, a REGISTER signal in which the registration valid time is specified by the Expires header is transmitted using the communication control unit 15. Thereby, user registration of the wireless IP telephone 10 is performed. By this processing, the registration information of the wireless IP telephone 10 is validated in the user information database 31 provided in the call control server 30. The wireless IP telephone 10 can be used on the IP telephone system only during the designated registration valid time.

<2-3. About incoming call control processing>
Here, the incoming call control processing of the wireless IP telephone 10 in the second embodiment of the present invention will be described with reference to the block diagrams of FIGS. 1 and 4 and the flowchart of FIG.

  The processing flow shown in FIG. 5 can be started at an arbitrary timing in a state in which the power supply of the wireless IP telephone 10 is activated and communication with the call control server 30 is possible. After the start of this process, the remaining capacity determination unit 17 checks the remaining capacity of the battery 16 in step S210. In step S220, it is determined whether or not the remaining capacity obtained by the confirmation exceeds a predetermined value.

  If it is determined in step S220 that the remaining capacity is lower than a predetermined value, the remaining capacity determination unit 17 checks the state of the remaining capacity shortage flag recorded in the memory 22 in step S230. When it is confirmed that the remaining capacity shortage flag is set to the valid state, the process proceeds to step S210, and the remaining battery capacity is confirmed again. Thereby, this process is continued.

  Conversely, when it is confirmed in step S230 that the remaining capacity shortage flag is set to an invalid state, the remaining capacity determination unit 17 sets the remaining capacity shortage flag recorded in the memory 22 to be valid in step S240. . Then, the deletion instructing unit 11c is notified that the remaining capacity has changed to an insufficient state.

  Upon receiving the notification, the deletion instruction unit 11c transmits a user registration deletion signal to the call control server 30 using the communication control unit 15 in step S250. As a result, the call control server 30 deletes the user registration of the wireless IP telephone 10. Then, the process proceeds to step S210, and the remaining battery capacity is checked again by the remaining battery capacity determination unit 17. Thereby, this process is continued.

  The description returns to step S220 again. When it is determined in step S220 that the remaining capacity exceeds a predetermined value, the remaining capacity determination unit 17 checks the state of the remaining capacity shortage flag recorded in the memory 22 in step S221. If it is confirmed that the remaining capacity shortage flag is set to the invalid state, the process proceeds to step S210, and the remaining battery capacity is confirmed again. Thereby, this process is continued.

  Conversely, if it is confirmed in step S221 that the remaining capacity shortage flag is set to the valid state, the remaining capacity determination unit 17 sets the remaining capacity shortage flag recorded in the memory 22 to invalid in step S222. . Then, it notifies the registration instruction unit 11d that the remaining capacity has changed from the insufficient state to the normal state.

  The registration instructing unit 11 d that has received the notification transmits a user registration signal to the call control server 30 using the communication control unit 15 in step S223. As a result, user registration of the wireless IP telephone 10 is performed, and the wireless IP telephone 10 can be used in the IP telephone system. Then, the process proceeds to step S210, and the remaining battery capacity is checked again by the remaining battery capacity determination unit 17. Thereby, this process is continued.

  This processing described above is normally terminated when the power of the wireless IP telephone 10 is stopped or when the battery runs out. However, it may be configured such that the processing can be interrupted at an arbitrary timing by providing an instruction receiving unit that receives a processing interruption instruction.

Next, a third embodiment of the present invention will be described with reference to the drawings.
[Embodiment 3]
<3-1. IP phone system configuration>
FIG. 6 is a block diagram showing a configuration of an IP telephone system including the wireless IP telephone 10 according to the third embodiment of the present invention. In addition, about the apparatus part of the same content as Embodiment 1, description shall be abbreviate | omitted by adding the same code | symbol. As a configuration different from that of the first embodiment, the radiotelephone IP telephone 10 includes a radio wave intensity determination unit 22 (= radio wave intensity determination means). Details of the radio wave intensity determination unit 22 will be described later.

<3-2. Internal configuration of wireless IP phone>
FIG. 7 is a block diagram showing the inside of the wireless IP telephone 10 according to the third embodiment of the present invention. In addition, about the apparatus part of the same content as Embodiment 1, description shall be abbreviate | omitted by adding the same code | symbol. As a configuration different from that of the first embodiment, a radio wave intensity determination unit 22 is provided. Further, the remaining capacity determination unit 17 is not provided. For this reason, the function of the incoming / outgoing possibility determination unit 11b is partially different.

  The radio wave intensity determination unit 22 periodically checks the radio wave intensity of the radio communication radio wave received by the antenna device 18 in the wireless LAN 42. Then, it is determined whether the radio wave intensity is lower than a predetermined value. As a standard for determining the predetermined value, it is desirable that the wireless IP telephone 10 has such a strength that the telephone call function and the communication request transmission / reception function via the wireless LAN 42 can be implemented without hindrance.

  In relation to the above, the incoming / outgoing determination unit 11b of this embodiment receives an incoming call detection notification from the call control server 30, and when the telephone number determination unit 11a determines that the incoming number is a group telephone number, The radio wave intensity determination unit 22 is instructed to perform the radio wave intensity determination process. Then, as a result of the radio field intensity determination process, if the radio field intensity is below a predetermined value, a signal indicating call rejection is transmitted to the call control server using the communication control unit 15. As a signal used for call rejection, for example, a busy notification signal indicating that the wireless IP telephone 10 is busy is used.

  Further, in the present embodiment, the radio wave intensity is insufficient to indicate that the radio wave intensity of the radio wave received by the antenna device 18 is less than a predetermined value (= the radio wave intensity is insufficient) in the memory 12. A flag is recorded. The radio wave intensity deficiency flag is set to be effective when the radio wave intensity determination unit 22 detects a radio wave intensity deficiency. The radio wave intensity deficiency flag is set invalid when the radio wave intensity determination unit 22 detects that the radio wave intensity deficiency has been resolved by the movement of the antenna device 18 or the change in direction.

<3-3. About incoming call control processing>
Here, the incoming call control processing of the wireless IP telephone 10 in the third embodiment of the present invention will be described with reference to the block diagrams of FIGS. 6 to 7 and the flowchart of FIG. In addition, about the process of the same content as Embodiment 1, description shall be abbreviate | omitted by adding the same process number.

  The processing flow shown in FIG. 8 can be started at an arbitrary timing in a state where the power source of the wireless IP telephone 10 is activated and communication with the call control server 30 is possible. Steps S110 to S130 and step S151 have the same contents as those in the first embodiment, and thus description thereof is omitted.

  If it is determined in step S130 that the incoming call number is a group telephone number, the telephone number determination unit 11a instructs the radio wave intensity determination unit 17 to perform radio wave intensity determination processing. Upon receiving the instruction, the radio wave intensity determination unit 22 measures the radio wave intensity of the communication radio wave received by the antenna device 18 in the wireless LAN 42 in step S310. Then, it is determined whether or not the radio wave intensity obtained by the measurement exceeds a predetermined value, and the determination result is given to the incoming / outgoing determination unit 11b.

  In response to the determination result, the incoming / outgoing determination unit 11b confirms the determination result of the radio wave intensity in step S320. As a result of the confirmation, if it is confirmed that the radio wave intensity is not lower than the predetermined value, the incoming call permission determination unit 11b proceeds to the above-described step S151. On the other hand, if it is confirmed in step S320 that the radio wave intensity is below the predetermined value, the incoming call availability determination unit 11b uses the communication control unit 15 to reject the incoming call to the call control server 30 in step S330. For example, a busy signal or the like is transmitted. Thereafter, the process proceeds to step S110, and this process is continued by entering the state of performing the incoming call detection process again.

  This processing described above is normally terminated when the power of the wireless IP telephone 10 is stopped or when the battery runs out. However, it may be configured such that the processing can be interrupted at an arbitrary timing by providing an instruction receiving unit that receives a processing interruption instruction.

Next, a fourth embodiment of the present invention will be described with reference to the drawings.
[Embodiment 4]
<4-1. IP phone system configuration>
Since it is the same content as Embodiment 3, description is abbreviate | omitted here <4-2. Internal configuration of wireless IP phone>
FIG. 9 is a block diagram showing the inside of the wireless IP telephone 10 according to the fourth embodiment of the present invention. In addition, about the apparatus part of the same content as Embodiment 1- Embodiment 3, description shall be abbreviate | omitted by adding the same code | symbol.

  As a configuration different from the first to third embodiments, when the radio field intensity determination process by the radio field intensity determination unit 22 is performed and the radio field intensity is below a predetermined value, the deletion instruction unit 11c. Is notified of the lack of radio field strength. Upon receiving the notification, the deletion instruction unit 11 c transmits a user registration deletion signal to the call control server 30 using the communication control unit 15. When the radio field intensity exceeds a predetermined value, the radio field intensity determination unit 22 notifies the registration instruction unit 11d that the radio field intensity is insufficient. Upon receiving the notification, the registration instruction unit 11 d transmits a user registration signal to the call control server 30 using the communication control unit 15.

<4-3. About incoming call control processing>
Here, the incoming call control processing of the wireless IP telephone 10 in the fourth embodiment of the present invention will be described with reference to the block diagrams of FIGS. 6 and 9 and the flowchart of FIG.

  The processing flow shown in FIG. 10 can be started at an arbitrary timing in a state where the power supply of the wireless IP telephone 10 is activated and communication with the call control server 30 is possible. After the start of this processing, the radio field strength confirmation unit 22 confirms the magnitude of the radio field strength of the radio wave received by the antenna device 18 from the wireless LAN 42 in step S410. In step S420, it is determined whether the radio wave intensity obtained by the confirmation exceeds a predetermined value.

  If it is determined in step S420 that the radio wave intensity is below a predetermined value, the radio wave intensity confirmation unit 22 checks the state of the radio wave intensity deficiency flag recorded in the memory 22 in step S430. If it is confirmed that the radio wave intensity deficiency flag is set to the valid state, the process proceeds to step S410, and the battery radio wave intensity is confirmed again. Thereby, this process is continued.

  On the other hand, when it is confirmed in step S430 that the radio wave intensity deficiency flag is set to an invalid state, the radio wave intensity confirmation unit 22 sets the radio wave intensity deficiency flag recorded in the memory 22 to be valid in step S440. . Then, it notifies the deletion instructing unit 11c that the radio field intensity has changed to an insufficient state.

  Upon receiving the notification, the deletion instruction unit 11c transmits a user registration deletion signal to the call control server 30 using the communication control unit 15 in step S450. Then, the process proceeds to step S410, and the battery radio field intensity is confirmed again by the radio field intensity confirmation unit 22. Thereby, this process is continued.

  Returning to step S420 again, if it is determined in step S420 that the radio field intensity exceeds a predetermined value, the radio field intensity confirmation unit 22 determines that the radio field intensity deficiency flag recorded in the memory 22 in step S421. Check the status of. If it is confirmed that the radio wave intensity deficiency flag is set to the invalid state, the process proceeds to step S410, and the battery radio wave intensity is confirmed again. Thereby, this process is continued.

  On the other hand, when it is confirmed in step S421 that the radio wave intensity deficiency flag is set to the valid state, the radio wave intensity confirmation unit 22 invalidates the radio wave intensity deficiency flag recorded in the memory 22 in step S422. . Then, it notifies the registration instruction unit 11d that the radio wave intensity has changed from the insufficient state to the normal state.

  The registration instruction unit 11 d that has received the notification transmits a user registration signal to the call control server 30 using the communication control unit 15 in step S423. Then, the process proceeds to step S410, and the battery radio field intensity is confirmed again by the radio field intensity confirmation unit 22. Thereby, this process is continued.

  This processing described above is normally terminated when the power of the wireless IP telephone 10 is stopped or when the battery runs out. However, it may be configured such that the processing can be interrupted at an arbitrary timing by providing an instruction receiving unit that receives a processing interruption instruction.

[About incoming call control sequence]
Here, a conventional incoming call control sequence executed by the wireless IP telephone 10 and the call control server 30 according to the first to fourth embodiments of the present invention will be described with reference to the sequence diagrams of FIGS. The sequence diagram shown in FIGS. 11 to 15 shows a communication sequence when SIP (Session Initiation Protocol), which is a typical call control protocol of the IP telephone system, is used. Note that the part of user authentication that is actually necessary in each sequence is omitted.

  FIG. 14 shows a conventional incoming call control sequence during normal communication. In FIG. 14, the wireless IP telephone 10a first selected from the call control server 30 accepts an incoming call detection signal (signal No. 3: INVITE) and responds to a call arriving at a group telephone number by a sequential search method. Communication sequence. At this time, no incoming call detection signal is transmitted to the wireless IP telephone 10b positioned at a lower selection order than the wireless IP telephone 10a.

  On the other hand, FIG. 11 shows an incoming call control sequence according to the first and third embodiments of the present invention. FIG. 11 shows a wireless IP telephone 10a that is first selected from the call control server 30 for a call that arrives at a group telephone number by the sequential search method (wireless IP telephone 10a according to the first and third embodiments). Is a communication sequence in the case of accepting an incoming call and responding. It is assumed that the wireless IP phone 10a is in a state where the remaining battery capacity is insufficient or the radio wave intensity is insufficient.

  In this state, when the receiving-side wireless IP telephone 10a receives an incoming notification signal from the call control server 30, it returns a busy signal (signal No. 5: 486 Busy Here) to the call control server 30, and within the group Response processing is entrusted to the other IP telephone. As a result, an incoming call notification signal (signal No. 7: INVITE) is sent to the radio IP telephone 10b selected next by the call control server 30. In other words, since the incoming signal is sent to a terminal other than the terminal that has fallen in the remaining battery tribe and the radio field strength, it is possible to reliably respond to the incoming call, and if the wireless IP telephone 10a responds. It is possible to avoid problems caused by insufficient battery power and insufficient radio field strength, such as voice quality degradation and unexpected abnormal operation.

  FIG. 15 shows a conventional incoming call control sequence when a communication abnormality occurs. FIG. 15 shows that a conventional wireless IP telephone 10a first selected from the call control server 30 for a call received to a group telephone number by the sequential search method is due to an extremely insufficient radio field strength or a shortage of remaining battery capacity. This is a communication sequence when communication is impossible.

  Since the call control server 30 cannot obtain a response from the wireless IP telephone 10a, the call control server 30 retransmits the incoming call notification signal for a certain period of time (this length varies depending on the call control server 30) (signals No. 3 to No. 3). 8). Thereafter, due to a retransmission timeout, the call control server 30 transfers the destination to the second selected wireless IP telephone 10b and transmits an incoming notification signal. This conventional method has a problem that a large delay occurs in communication because the incoming notification signal is retransmitted to the wireless IP telephone 10a repeatedly.

  On the other hand, FIG.12 and FIG.13 has shown the incoming call | requirement control sequence in Embodiment 2 and Embodiment 4 of this invention. FIG. 12 shows a communication sequence for user registration and user registration deletion. The call control server 30 has a database (= user information database) in which user information (= information on each IP telephone) is stored, and the IP telephone 10a uses a REGISTER signal that specifies the registration valid time in the Expires header. Is registered to the call control server.

  By this processing, the registration information on the call control server 30 side is validated, and the IP telephone 10a can be used on the IP telephone system. When the time specified in the Expires header elapses after user registration, the registration information on the call control server side 30 is automatically invalidated and the IP telephone 10a becomes unusable. It is necessary to re-register user information. Also, user registration can be deleted from the IP telephone 10a side by transmitting a REGISTER signal in which 0 is specified in the Expires header.

  As a result, the registration information on the call control server side is invalidated, and thereafter, the IP telephone 10a becomes unusable on the IP telephone system (however, this is not the case when the IP telephone 10a is registered in a plurality of groups). Absent). In this state, if there is an incoming call to the IP telephone 10a, the call control server side performs appropriate processing, for example, processing for transferring the destination to another IP telephone, and the like to the IP telephone 10a. On the other hand, the incoming call detection signal is not transmitted.

  In the second embodiment, the user registration of the IP telephone 10a is temporarily deleted using the sequence of FIG. 12 when the battery is in a low battery state and in the fourth embodiment, the radio wave intensity is insufficient. Conversely, when the state is recovered, user registration is performed again using the sequence of FIG. Note that in an IP telephone having a plurality of group telephone numbers, the above-described processing is executed independently for each group telephone number.

  FIG. 13 shows a case where the wireless IP telephone 10a first selected from the call control server when an incoming call is made to a group telephone number by the sequential search method is an IP telephone whose user registration has been deleted by the user registration deletion communication sequence shown in FIG. This is a communication sequence in some cases. The wireless IP telephone 10a deletes the user registration according to the sequence shown in FIG. 12 when it detects that the remaining battery capacity is insufficient or the radio wave intensity is insufficient. Therefore, when a group telephone number is received, the incoming call notification signal is transmitted from the call control server to the next candidate, the wireless IP telephone 10b, without being transmitted to the wireless IP telephone 10a.

  Therefore, in the present invention, it is possible to avoid the occurrence of delay as shown in FIG. Further, the network load is not generated due to the extra delay, and the connection quality and reliability of the group telephone number or the entire IP telephone system can be improved.

[Other embodiments]
The present invention has been described with reference to the preferred embodiments and examples. However, the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea. be able to.

Therefore, the present invention can also be applied to the following embodiments.
(A) In the present embodiment, SIP is used as a signaling protocol for communication between the wireless IP telephone 10 and the call control server 30, but the present invention is also implemented in an IP telephone system using a signaling protocol other than this. It may be.

  (B) In the present embodiment, the configuration in which each functional unit related to the incoming call control processing is provided in the wireless IP telephone 10 has been described as an example. However, a part of these functional units is a network such as a telephone network or a LAN. It may be a form realized by an external device connected via the network. For example, the telephone number determination unit 11a may be mounted on an information processing apparatus (such as a network server) that exists on the network. Thereby, for example, it is possible to collectively change the telephone number information for determining whether the telephone number is a group telephone number.

  (C) In the present embodiment, the wireless IP telephone 10 is taken as an example of a communication apparatus having the incoming call control method of the present invention, but any other apparatus can be used as long as it is a communication apparatus connectable to the wireless IP telephone system. In the embodiment, the present invention may be implemented. For example, the present invention may be implemented in an information processing apparatus such as a wireless facsimile apparatus, a mobile phone with a wireless LAN connection function, an Internet telephone, a PDA or a notebook computer having a wireless communication function.

  (D) In this embodiment, various functional units of the wireless IP telephone set 10 related to the incoming call control system of the present invention are realized by executing a program on an arithmetic processing unit such as a microprocessor. May be realized by a plurality of circuits.

These are block diagrams which show the structure of the radio | wireless IP telephone system which concerns on 1st and 2nd embodiment of this invention. These are block diagrams which show the structure of the wireless IP telephone set which concerns on 1st embodiment of this invention. These are the flowcharts which show the processing flow of the incoming call control processing which concerns on 1st embodiment of this invention. These are block diagrams which show the structure of the radio | wireless IP telephone which concerns on 2nd embodiment of this invention. These are flowcharts which show the processing flow of the incoming call control processing which concerns on 2nd embodiment of this invention. These are block diagrams which show the structure of the radio | wireless IP telephone system which concerns on 3rd and 4th embodiment of this invention. These are block diagrams which show the structure of the radio | wireless IP telephone set which concerns on 3rd embodiment of this invention. These are flowcharts which show the processing flow of the incoming call control processing which concerns on 3rd embodiment of this invention. These are block diagrams which show the structure of the radio | wireless IP telephone set which concerns on 4th embodiment of this invention. These are flowcharts which show the processing flow of the incoming call control processing which concerns on 4th embodiment of this invention. These are sequence diagrams showing an incoming call control sequence according to the first and third embodiments of the present invention. These are the sequence diagrams which show the communication sequence of the user registration and user registration deletion which concern on 2nd and 4th embodiment of this invention. These are sequence diagrams showing an incoming call control sequence according to the second and fourth embodiments of the present invention. These are sequence diagrams showing a conventional incoming call control sequence during normal communication. These are the sequence diagrams which show the incoming call control sequence at the time of the conventional communication abnormality occurrence.

Explanation of symbols

10 wireless IP telephone 11a telephone number determination unit (phone number determination means)
11b Incoming / outcoming decision unit (incoming / outgoing decision unit)
11c Deletion instruction section (deletion instruction means)
11d Registration instruction section (registration instruction means)
15 Communication control unit (communication control means)
17 Remaining capacity determination unit (remaining capacity determination means)
18 Antenna device (wireless communication means)
22 Radio field strength judging section (Radio wave strength judging means)
30 Call control server 31 User information database (group management information)
42 Wireless communication network (wireless LAN)

Claims (7)

Wireless communication means connectable to a wireless communication network;
A server that records group management information in which a group telephone number, which is a telephone number that can be shared by a plurality of IP telephones, is associated with an IP telephone, accepts an incoming call to the group telephone number, and associates the group telephone number with the group telephone number A communication control means for communicating with the call control server for determining the received IP telephone using the group management information and providing an incoming call detection notification;
A radio IP telephone comprising: radio field strength determination means for measuring radio field intensity of radio waves received from the radio communication network by the radio communication unit and determining whether the radio field intensity is below a predetermined value; ,
Telephone number determination means for determining whether the destination telephone number is the group telephone number when the communication control means receives the incoming call detection notification from the call control server;
An incoming / outgoing determination unit that determines the radio field intensity using the radio field intensity determination unit when the telephone number determination unit determines that the destination telephone number is the group telephone number;
When it is determined that the radio wave intensity is lower than a predetermined value as a result of the determination of the radio field strength, the incoming / outgoing possibility determination unit uses the communication control unit to send a signal indicating rejection of the incoming call to the call control server. A wireless IP telephone characterized by transmitting. Deletion instructing means for instructing the call control server to delete information related to the wireless IP telephone from the group management information when the radio field intensity determining means determines that the radio field intensity is below a predetermined value. When,
Registration instruction means for instructing the call control server to register information related to the wireless IP telephone in the group management information when the radio field intensity determination means determines that the radio field intensity exceeds a predetermined value. The wireless IP telephone according to claim 3, further comprising: A wireless IP phone, wherein if it is determined that the radio field intensity is below a predetermined value, an incoming call from the call control server is rejected. A wireless IP telephone that transmits a busy signal to a call control server when it is determined that the radio wave intensity is below a predetermined value. A system comprising at least first and second wireless IP telephones and a call control server;
When there is an incoming call from an outside line and the radio field intensity of the radio wave received by the first IP telephone falls below a predetermined value, the call control server does not transmit a call signal to the first radio IP telephone, A wireless IP telephone system, wherein a calling signal is transmitted to a second wireless IP telephone. A system comprising at least first and second wireless IP telephones and a call control server;
When there is an incoming call from an outside line and the radio field intensity of the radio wave received by the first IP telephone falls below a predetermined value, the first IP telephone receives the first IP telephone by the call control server. When a signal indicating that the radio wave intensity is below a predetermined value is transmitted and the call control server receives the signal, the call control server does not transmit a call signal to the first IP telephone, and the second IP telephone A wireless IP telephone system, wherein a call signal is transmitted to A system comprising at least first and second wireless IP telephones and a call control server;
When there is an incoming call from an outside line and the radio field intensity of the radio wave received by the first IP telephone falls below a predetermined value, the first IP telephone transmits a busy signal to the call control server, and the call control When the server receives the signal, the server does not transmit a call signal to the first IP telephone but transmits a call signal to the second IP telephone.

Images