JP2008042767A - Video telephone system and gateway and ip video telephone terminal used in it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a video telephone system configured such that the state where display video images are disturbed does not continue regardless of the fetch error of the head of video data. <P>SOLUTION: The video telephone system includes the gateway, the IP video telephone terminal connected through an IP network to the gateway, and a video telephone terminal for a switching network connected through the switching network to the gateway. The gateway is provided with a connection destination information notifying means 14 for sending out a connection destination information message indicating that a connection destination is the video telephone terminal for the switching network to the IP video telephone terminal in response to the request of a call for which the IP video telephone terminal and the video telephone terminal for the switching network communicate, and a switching network side image control information transmission means 15 for transmitting image control information to the video telephone terminal for the switching network. The IP video telephone terminal is provided with an image control request means for transmitting an image control request to the opposing video telephone terminal 40 for the switching network to the gateway in response to the connection destination information message. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a videophone system in which a gateway, an IP videophone terminal, and a videophone terminal for an exchange network are connected to an IP network and a circuit switched network, and a gateway and an IP videophone terminal used in the videophone system. .

  In recent years, IP telephones have become widespread, and IP videophone services over the IP network are being studied. On the other hand, as a video phone, a service is conventionally performed via a circuit switching network. When an IP video phone service is performed, integration with the circuit switching network side becomes a problem.

In contrast to the above, compatibility is ensured by using standard call control protocols such as SIP, H323, and MEGACO, and communication between terminals of different manufacturers is ensured, and a unique function is realized by using a unique call control method. Japanese Patent Application Laid-Open No. H10-228688 discloses an IP terminal device that performs this.
JP 2004-328195 A

  However, the video / audio codec required to make a videophone call due to the difference in protocol between an IP videophone terminal that employs SIP for call control and an existing videophone terminal that employs 3G-324M for call control, for example. The timing for determining the terminal capability information such as, etc. differs depending on the negotiation with the partner terminal, but when the call connection is completed so that the call connection is established while maintaining consistency with this, the video / audio data transmission start and reception start timing Deviation occurs. For this reason, in either the IP videophone terminal or the existing telephone terminal, a mistake in taking in the head of the video data transmitted from the partner terminal occurs. In existing videophones, the transmission interval of I-frames is not specified, and the movement of the subject is often small. Therefore, in the terminal that missed the capture of the first I-frame data, the display video is displayed when the I-frame is not transmitted for a long time. There is a problem that the disordered state continues.

  The problem to be solved by the invention is that due to the difference in call control protocol, when the call connection is completed, there is a difference in the start timing of video / audio data transmission and reception start timing, and the beginning of the video data transmitted from the partner terminal is detected. An error occurs and the display video is disturbed. The object of the present invention is that an acquisition error occurs at the beginning of the video data transmitted from the partner terminal due to a difference in the call control protocol. Nevertheless, it is an object of the present invention to provide a videophone system configured so that a state in which a display image is disturbed does not continue, and to provide a gateway and an IP videophone terminal used for the videophone system. .

  The videophone system according to the present invention includes a gateway connected to an IP network and a circuit switching network, an IP videophone terminal connected to the gateway via the IP network, and a connection to the gateway via the switching network. In the videophone system comprising the switched videophone terminal, the gateway is configured to respond to a call request for a call between the IP videophone terminal and the switched videophone terminal. Connection destination information notifying means for sending a connection destination information message indicating that the connection destination is a switching network videophone terminal, and image control information to the switching network videophone terminal in response to a request from the IP videophone terminal Switching network side image control information transmitting means, and the IP videophone terminal responds to the connection destination information message according to the connection destination information message. Wherein the image control requests to exchange videophone terminal for network that is equipped with image control request means for transmitting to said gateway.

  The gateway according to the present invention is connected to the gateway connected to the gateway via the IP network and the circuit switching network, the IP videophone terminal connected to the gateway via the IP network, and the gateway via the switching network. A gateway of a videophone system including a switched network videophone terminal, wherein the IP videophone terminal responds to a call request for a call between the IP videophone terminal and the switched network videophone terminal. Connection destination information notifying means for sending a connection destination information message indicating that the connection destination is a videophone terminal for the switching network, and image control information to the videophone terminal for the switching network in response to a request from the IP videophone terminal. And an exchange network side image control information transmitting means for transmitting.

  An IP videophone terminal according to the present invention is connected to an IP network and a circuit switching network, the gateway according to claim 4, an IP videophone terminal connected to the gateway via the IP network, and the switching network. An IP videophone terminal of a videophone system including an exchange videophone terminal connected to the gateway via the gateway, wherein the IP videophone terminal responds to the connection destination information message. An image control requesting means for transmitting an image control request to the opposite switching network videophone terminal to the gateway is provided.

  In the videophone system according to the present invention, the gateway is connected to the IP videophone terminal in response to a call request for a call between the IP videophone terminal and the switched network videophone terminal. The IP videophone terminal transmits an image control request to the opposite switching network videophone terminal in response to the connection destination information message to the gateway in response to the connection destination information message. Since image control information is sent to the videophone terminal for the switching network in response to a request from the telephone terminal, the exchange is performed even though a mistake in capturing the head of the video data transmitted from the other terminal occurs due to a difference in protocol. Image control information is sent to the network videophone terminal, and the I-frame can be sent from the videophone terminal for the switched network accordingly. Next, it is possible to stop the continuation of image disturbance.

  The gateway according to the present invention provides a connection destination information message indicating that a connection destination to an IP videophone terminal is a videophone terminal for an exchange network in response to a call request between the IP videophone terminal and the videophone terminal for an exchange network. , And image control information is transmitted to the switching network videophone terminal in response to a request from the IP videophone terminal, so that a mistake in taking in the head of the video data transmitted from the partner terminal occurs due to a difference in protocol. In this case, it is guaranteed that the image control information is sent to the videophone terminal for the switching network, and the I-frame can be sent from the videophone terminal for the switching network accordingly. It becomes possible to stop the continuation of the disturbance of the image.

  Since the IP videophone terminal according to the present invention transmits an image control request to the opposite switching network videophone terminal to the gateway in response to the connection destination information message, the gateway according to claim 4 responds to this request. The image control information is transmitted to the videophone terminal for the switching network, and it is ensured that the image control information is sent to the videophone terminal for the switching network. Thus, it is possible to stop the continuation of video disturbance in the IP videophone terminal.

  Embodiments of a videophone system according to the present invention and gateways and IP videophone terminals used therein will be described below with reference to the accompanying drawings. In the drawings, the same components are denoted by the same reference numerals and redundant description is omitted. FIG. 1 shows a block diagram of a videophone system according to the present invention. The gateway 10 is connected to an IP network 21 and a circuit switching network 22. The IP videophone terminal 30 is connected to the gateway 10 via the base station A and the IP network 21. The switching network videophone terminal 40 is connected to the gateway via the base station B and the switching network 22.

  In the above, the IP videophone terminal 30 uses SIP (Session Initiation Protocol) for call control, and the switching network videophone terminal 40 uses 3G-324M (used in third-generation mobile communication) for call control. This is an audio-visual communication standard that uses MPEG4 as the video compression method and AMR as the audio compression method. The gateway 10 uses SIP for call control with the IP videophone terminal 30 and uses 3G-324M for call control with the switching network videophone terminal 40.

  FIG. 2 is a block diagram showing a configuration of the switching network videophone terminal 40. The switching network videophone terminal 40 includes an audio output unit 31 such as a speaker and an audio input unit 32 such as a microphone. The audio output unit 31 and the audio input unit 32 are connected to an audio codec 36 that encodes an audio signal and decodes decoded audio data.

  The switching network videophone terminal 40 includes a monitor 33 such as an LCD or a CRT, and a camera 34. A video signal captured by the camera 34 is converted into digital data for encoding by a signal conversion unit 35. The digital data decoded by the video codec 37 is converted into a video signal of a predetermined system such as NTSC by the signal converter 35. The video codec 37 decodes the video data and encodes the digital data sent from the signal conversion unit 35.

  The switching network videophone terminal 40 includes a network interface 39 and a multiplexing / demultiplexing unit 38 connected to the network interface 39. The network interface 39 is an interface connected to a network (IP network 21 or circuit switching network 22), and the network access control unit 44 performs network control via the network interface 39. A wireless or wired communication unit is connected to the network interface 39.

  The multiplexing / demultiplexing unit 38 demultiplexes the multiplexed data coming from the network side, and transmits the audio data to the audio codec 36, the video data to the video codec 37, and the call control information to the interconnection procedure control unit 43. To do. Conversely, the output of the audio codec 36 and the output of the video codec 37 are multiplexed and transmitted via the network interface 39. Note that a delay circuit is provided between the multiplexing / demultiplexing unit 38 and the audio codec 36 in order to synchronize video data and audio data, but is omitted here.

  An interconnection procedure control unit 43 is connected to the multiplexing / demultiplexing unit 38, and the interconnection procedure control unit 43 performs call control using a 3G-324M protocol. A main control unit 41A is connected to the interconnection procedure control unit 43, network access control unit 44, and video codec 37. The main control unit 41A includes these interconnection procedure control unit 43, network access control unit 44, video codec. 37 is controlled. The main control unit 41A is connected to an operation unit 42 for performing on-hook and off-hook and telephone number input.

  The main control unit 41A is provided with image control request means 4A. The image control request unit 4A transmits an image control request to the IP videophone terminal 30 to the gateway 10. Here, the video / audio data is received before the transmission / reception capability is determined with the gateway 10. When it arrives, it is configured to transmit an I-frame transmission image control request to the gateway 10.

  FIG. 3 shows a configuration block diagram of the IP videophone terminal 30. The components of the IP videophone terminal 30 are functionally the same in many parts as the videophone terminal 40 for the switching network, and the network access control unit 44 and the multiplexing / demultiplexing unit 38 of the videophone terminal 40 for the switching network Instead, it can be considered that the protocol processing / packet processing unit 46 is provided. The protocol processing / packet processing unit 46 performs processing such as UDP protocol processing, IP protocol processing, header addition / deletion, etc. Data sent from the audio codec 36, the video codec 37, and the interconnection procedure control unit 48 is IP A packet that is processed so as to be transmitted to the network 21 and that is sent from the IP network 21 is subjected to UDP protocol processing, IP protocol processing, header deletion, etc., and the corresponding data is transmitted to the audio codec 36, the video codec 37, and the interconnection procedure control unit. Send to 48 required ones. The interconnection procedure control unit 48 performs call control using the SIP protocol.

  The main control unit 41B is provided with image control requesting means 4B. The image control request unit 4B transmits an image control request to the opposite switching network videophone terminal 40 to the gateway 10 in response to the connection destination information message sent from the gateway 10.

  FIG. 4 shows a main configuration of the gateway 10. The gateway 10 includes an IP network corresponding unit 11, a circuit switched network corresponding unit 12, and a control unit 13. The IP network support unit 11 performs call control using the SIP protocol, and the circuit switched network support unit 12 performs call control using the 3G-324M protocol.

  The control unit 13 includes a connection destination information notification unit 14, an exchange network side image control information transmission unit 15, and an IP network side image control information transmission unit 16. The connection destination information notification means 14 confirms that the connection destination to the IP videophone terminal 30 is the exchange network videophone terminal 40 in response to a call request for a call between the IP videophone terminal 30 and the exchange network videophone terminal 40. The connection destination information message shown is sent out. The switching network side image control information transmitting means 15 transmits image control information to the switching network videophone terminal 40 in response to a request from the IP videophone terminal 30. Here, image control information for I frame transmission is transmitted as the image control information.

  The IP network side image control information transmitting means 16 transmits image control information to the IP videophone terminal 30 in response to a request from the switching network videophone terminal 40. As shown in FIG. 4, between the IP network corresponding unit 11 and the circuit switched network corresponding unit 12, a path 17 for passing video / audio data from the IP network corresponding unit 11 to the circuit switched network corresponding unit 12 and a circuit And a path 18 through which video / audio data passes from the exchange network support unit 12 to the IP network support unit 11.

  The operation of the videophone system configured as described above will be described with reference to a sequence diagram. In each sequence diagram, a message between the IP videophone terminal 30 and the gateway 10 indicates a SIP message, and the notation indicates a method or a status code. A message with an indication of SDP means that terminal capability information is included. On the other hand, the message between the switching network videophone terminal 40 and the gateway 10 is H.264. The abbreviation of the message is as shown in FIG. In each sequence diagram, an arrow indicated by a broken line represents an AT command for bearer connection. In the figure, the IP videophone terminal 30 may be referred to as a SIP terminal and the switching network videophone terminal 40 may be referred to as a 324M terminal because of space limitations.

  There are several possible patterns for the call control message transmission / reception sequence leading to call establishment between the IP videophone terminal 30 and the switching network telephone terminal 40. An example of making a call from the IP videophone terminal 30 is shown in FIG. 6 and FIG. As shown in the top part of FIG. 6, when a connection request message INVITE (SDP) including terminal capability information is sent from the IP videophone terminal 30 to the gateway 10 by the SIP protocol (S11 in FIG. 6), the connection request message INVITE (SDP) is sent earlier. By receiving the telephone number of the other party from the IP videophone terminal 30, in the control unit 13 of the gateway 10 that operates the circuit switching network corresponding unit 12, the connection destination information notification means 14 is connected to the IP videophone terminal 30. An INVITE response (100 Trying), which is a connection destination information message indicating that the connection destination is the exchange network videophone terminal 40, is sent to the IP videophone terminal 30 in response to a call request for a call with the exchange network videophone terminal 40. The data is sent from the network corresponding unit 11 (S12). Here, in this embodiment, the connection destination information is included in the INVITE response (100 Trying), but the message for notifying the connection destination information may be any message as long as it is a response message to the INVITE received by the IP videophone terminal 30. .

  The message header of the INVITE response (100 Trying) is, for example, as shown in FIG. 8, and in the second line up from the last line, the terminal that performs call control using the 3G-324M protocol is the connection destination terminal. It is shown. In this embodiment, information on the connection destination terminal is added in the header part of the SIP message, but connection destination terminal information may be added in the body part of the SIP message. After this INVITE response (100 Trying) message is transmitted from the gateway 10, the IP videophone terminal 30 and the switching network videophone terminal 40 use the SIP protocol and the 3G-324M protocol respectively with the gateway 10. As the call control procedure proceeds and the exchange network videophone terminal 40 and the gateway 10 determine the transmission / reception capability as shown in the upper right part of FIG. Transmission of video / audio data is started (S13).

  However, between the IP videophone terminal 30 and the gateway 10, determination of transmission / reception capability is not completed at the same time as the start of transmission of video / audio data indicated by S 13, and the IP videophone terminal finally The acknowledgment response ACK is returned from 30 to the gateway 10, and the call control procedure is completed (S14).

  Therefore, after the call control procedure between the IP videophone terminal 30 and the gateway 10 is completed, the video / audio data arriving from the switching network videophone terminal 40 to the IP videophone terminal 30 via the path 18 in FIG. As for (S15), the IP videophone terminal 30 cannot receive the head part.

  Therefore, the image control requesting means 4B in the main control unit 41B of the IP videophone terminal 30 includes an Iframe transmission image control request in the confirmation response ACK to the opposite switching network videophone terminal 40 in response to the connection destination information message. To the gateway 10 (S14). FIG. 9 shows an example of the ACK message header. In the ACK message header, an image control request relating to retransmission of the I frame is described in the second line from the last line. In this embodiment, information on the connection destination terminal is added in the header part of the SIP message, but connection destination terminal information may be added in the body part of the SIP message.

  Upon receipt of the confirmation response ACK including the I frame transmission image control request, the control unit 13 of the gateway 10 interprets the Proxy-Require header field and sends the video Fast Update Picture MC to the switching network videophone terminal 40. (Miscellaneous Command) is transmitted to request I frame retransmission (S16: switching network side image control information transmitting means 15). In response to this, the main control unit 41A of the switching network videophone terminal 40 controls the video codec 37 to create an I frame, and the switching network videophone terminal 40 transmits the I frame (S17). . In this embodiment, connection destination terminal information is included in the Proxy-Require header field, but connection destination terminal information may be added in another header field.

  It should be noted that the progress of the protocol shown in FIGS. 6 and 7 is as shown in the figure in a certain state. The progress of the protocol between the IP videophone terminal 30 and the gateway 10 and the TV for the switching network are shown. It does not indicate that the protocol progress between the telephone terminal 40 and the gateway 10 is synchronized.

  FIGS. 6 and 7 show an example of making a call from the IP videophone terminal 30, but FIGS. 10 and 11 show an example of making a call from the videophone terminal 40 for the switching network. When a call is made from the switching network videophone terminal 40, the gateway 10 detects that the called party is the IP videophone terminal 30 and the calling party is the switching network videophone terminal 40, and starts the SIP protocol for the first time. Using the Supported header field of the INVITE message, it is possible to indicate that the connection destination is a videophone terminal for an exchange network. In the present embodiment, the connection destination terminal information is included in the Supported header field, but the connection destination terminal information may be added in another header field.

  Therefore, the connection destination information notifying means 14 of the gateway 10 is connected to the IP videophone terminal 30 in response to a call request for a call between the IP videophone terminal 30 and the exchange network videophone terminal 40. INVITE, which is a connection destination information message indicating that it is, is sent from the IP network corresponding unit 11 side (S21). FIG. 12 shows a header example of the INVITE message used above. In the fourth line upward from the last line in the figure, it is shown that the terminal that performs call control using the 3G-324M protocol is the connection destination terminal.

  After the INVITE message is transmitted from the gateway 10, the IP videophone terminal 30 and the switching network videophone terminal 40 perform a call control procedure between the gateway 10 and the SIP protocol using the SIP protocol and the 3G-324M protocol, respectively. As shown in the upper right part of FIG. 11, the transmission / reception capability determination is completed between the exchange network videophone terminal 40 and the gateway 10, and the video / audio data is received from the exchange network videophone terminal 40. Is started (S22).

  However, between the IP videophone terminal 30 and the gateway 10, the transmission / reception capability is not determined at the same time as the transmission of the video / audio data indicated by S22. In response to the off-hook at 30, an IPV telephone terminal 30 sends an INVITE response (200 OK) message to the gateway 10 to complete the call control procedure (S23).

  Therefore, after the call control procedure between the IP videophone terminal 30 and the gateway 10 is completed, the video / audio data arriving from the switching network videophone terminal 40 to the IP videophone terminal 30 via the path 18 in FIG. With regard to (S24), the IP videophone terminal 30 cannot receive the leading part.

  Therefore, the image control request means 4B in the main control unit 41B of the IP videophone terminal 30 sends an Iframe transmission image control request to the opposite switching network videophone terminal 40 in response to the connection destination information message. ) And return to the gateway 10 (S23). FIG. 13 shows an example of an INVITE response (200 OK) message header. In the INVITE response (200 OK) message header, the image control request relating to retransmission of the I frame is described in the second line from the last line.

  In response to the INVITE response (200 OK) message including the image control request for I frame transmission, the control unit 13 of the gateway 10 interprets the Proxy-Require header and sends a video Fast Update to the videophone terminal 40 for the switching network. A Picture MC (Miscellaneous Command) is transmitted to request I frame retransmission (S25: switching network side image control information transmitting means 15). In response to this, the main control unit 41A of the switching network videophone terminal 40 controls the video codec 37 to create an I frame, and the switching network videophone terminal 40 transmits the I frame (S26). . In this embodiment, connection destination terminal information is included in the Proxy-Require header field, but connection destination terminal information may be added in another header field.

  The protocol progress shown in FIGS. 10 and 11 also shows that the protocol progresses as shown in a certain state, and the protocol progress and exchange between the IP videophone terminal 30 and the gateway 10 are shown. It does not indicate that the progress of the protocol between the network videophone terminal 40 and the gateway 10 is synchronized. Therefore, the progress of the protocol between the IP videophone terminal 30 and the gateway 10 and the progress of the protocol between the switching network videophone terminal 40 and the gateway 10 may be as shown in FIGS. .

  The messages used in FIG. 14 are the same as those in FIGS. 10 and 11, and as shown in the upper left part of FIG. 15, the IP videophone terminal 30 corresponds to the off-hook in the IP videophone terminal 30. An INVITE response (200 OK) message is sent from the gateway 10 to the gateway 10 (S31). In response to this, an acknowledgment ACK is returned from the gateway 10 to complete the call control procedure (S32). Thereby, transmission of video / audio data from the IP videophone terminal 30 is started (S33).

  However, between the exchange network videophone terminal 40 and the gateway 10, the determination of the transmission / reception capability is not completed at the same time as the transmission of the video / audio data indicated by S33. The determination is completed, and finally an acknowledgment ACK is sent from the switching network videophone terminal 40 to the gateway 10 to complete the call control procedure (S35).

  For this reason, after the call control procedure between the switching network videophone terminal 40 and the gateway 10 is completed, the video image arriving from the IP videophone terminal 30 to the switching network videophone terminal 40 via the path 17 in FIG. With respect to the audio data (S34), the switching network videophone terminal 40 cannot receive the head portion.

  Therefore, the image control requesting means 4A in the main control unit 41A of the switching network videophone terminal 40 responds to the opposite IP videophone terminal 30 in response to the arrival of video / audio data when the transmission / reception capability is not yet determined. In order to make an image control request for I frame transmission, an MC (Miscellaneous Command) of video Fast Update Picture is transmitted to the gateway 10 to request I frame retransmission (S36).

  Upon receiving the MC including the image control request for I frame transmission, the control unit 13 of the gateway 10 transmits an INFO message to the IP videophone terminal 30 to request I frame retransmission (S37: IP network side image). Control information transmitting means 16). FIG. 16 shows an example of the INFO message. In the last line of the figure, a message relating to an I-frame transmission image control request is added. In response to this, the main control unit 41B of the IP videophone terminal 30 controls the video codec 37 to create an I frame, and the IP videophone terminal 30 transmits the I frame (S38). In this embodiment, I frame retransmission is requested by an INFO message, but I frame retransmission may be requested by using a message of another method such as UPDATE, INVITE (Re-INVITE).

  As described above, the IP videophone terminal and the switching network videophone terminal can receive the I frame even when a capture error occurs at the head of the video data transmitted from the counterpart terminal due to a difference in the call control protocol. As a result, it is possible to shorten the time that the video is disturbed after the display is started.

  In the above description, I frame retransmission is described in the interconnection between the IP videophone terminal 30 and the switching network videophone terminal 40. However, the video codec 37 is controlled with respect to image quality such as image quality priority or motion priority. Can do. When control is performed from the videophone terminal 40 for the switching network to the IP videophone terminal 30, as shown in S 36 and S 37 in FIG. 15, the video temporary terminal of the H.245 video Temporal Spatial Trade Off is set from the videophone terminal 40 for the switching network. This can be realized by setting image control information in MC (Miscellaneous Command) and sending it to the gateway 10, and sending an INFO message in which the image control information is set from the gateway 10 to the IP videophone terminal 30. Further, when control is performed from the IP videophone terminal 30 to the videophone terminal 40 for the switching network, an INFO message in which image control information is set is transmitted from the IP videophone terminal 30 to the gateway 10, and the switching network This can be done by setting the image control information to the MC (Miscellaneous Command) of H.245 video Temporal Spatial Trade Off and transmitting it to the videophone terminal 40. With respect to the control relating to the image quality such as the image quality priority or the motion priority, the IP videophone terminal 30 and the switching network videophone terminal 40 are provided with a control instruction key and the like, and the user operates this key to transmit the message. It is configured so that

The block diagram of the Example which concerns on the videophone system which concerns on this invention. The block diagram which shows the structure of the videophone terminal for switching networks which comprises the videophone system which concerns on this invention. The block diagram which shows the structure of the IP videophone terminal which comprises the videophone system which concerns on this invention. The block diagram which shows the principal part structure of the gateway used for the video telephone system which concerns on this invention. H.C. used in the videophone system according to the present invention. The figure which shows the abbreviation and full spell of the message in H.245 message. The figure which shows the sequence of the call control message performed between the IP video telephone terminal of the video telephone system which concerns on this invention, and the telephone terminal for switching networks. The figure which shows the sequence of the call control message performed between the IP video telephone terminal of the video telephone system which concerns on this invention, and the telephone terminal for switching networks. The figure which shows an example of the message header of the INVITE response (100 Trying) used in the sequence of the call control message in FIG. 7, FIG. The figure which shows an example of the ACK message header used in the sequence of the call control message in FIG. 7, FIG. The figure which shows the sequence of the call control message performed between the IP video telephone terminal of the video telephone system which concerns on this invention, and the telephone terminal for switching networks. The figure which shows the sequence of the call control message performed between the IP video telephone terminal of the video telephone system which concerns on this invention, and the telephone terminal for switching networks. The figure which shows an example of the header of the INVITE message used in the sequence of the call control message in FIG. 10, FIG. The figure which shows an example of the INVITE response (200 OK) message header used in the sequence of the call control message in FIG. 10, FIG. The figure which shows the sequence of the call control message performed between the IP video telephone terminal of the video telephone system which concerns on this invention, and the telephone terminal for switching networks. The figure which shows the sequence of the call control message performed between the IP video telephone terminal of the video telephone system which concerns on this invention, and the telephone terminal for switching networks. The figure which shows an example of the INFO message used in the sequence of the call control message in FIG. 14, FIG.

Explanation of symbols

4A, 4B Image control request means 10 Gateway 11 IP network corresponding section 12 Circuit switched network corresponding section 13 Control section 14 Connection destination information notifying means 15 Circuit switched network side image control information transmitting means 16 IP network side image control information transmitting means 21 IP Network 22 Circuit switching network 30 IP videophone terminal 31 Audio output unit 32 Audio input unit 33 Monitor 34 Camera 35 Signal conversion unit 36 Audio codec 37 Video codec 38 Multiplexing / demultiplexing unit 39, 47 Network interface 40 Videophone terminal for circuit switching network 41A, 41A Main control unit 42 Operation units 43, 48 Interconnection procedure control unit 44 Network access control unit 46 Protocol processing / packet processing unit

Claims (5)

A gateway connected to an IP network and a circuit-switched network; an IP videophone terminal connected to the gateway via the IP network; and a videophone terminal for a switched network connected to the gateway via the exchange network; In a videophone system configured to include:
The gateway connects to the IP videophone terminal in response to a call request for a call between the IP videophone terminal and the switching network videophone terminal. Connection destination information notifying means for transmitting the image data, and switching network side image control information transmitting means for transmitting image control information to the switching network videophone terminal in response to a request from the IP videophone terminal,
The IP videophone terminal comprises a videophone control request means for transmitting an image control request to an opposite switching network videophone terminal in response to the connection destination information message to the gateway. system. 2. The videophone system according to claim 1, wherein the image control request means transmits an I frame transmission image control request to the gateway in response to a connection destination information message. The videophone terminal for switching network includes image control request means for transmitting an image control request to the IP videophone terminal to the gateway, and before the determination of transmission / reception capability with the gateway is completed, the video / audio When data arrives, an image control request for I frame transmission is transmitted to the gateway,
2. The IP network side image control information transmitting means for transmitting image control information to an IP videophone terminal in response to a request from the switching network videophone terminal. Or the videophone system according to 2. A gateway connected to an IP network and a circuit-switched network; an IP videophone terminal connected to the gateway via the IP network; and a videophone terminal for a switched network connected to the gateway via the exchange network; A gateway for a videophone system comprising:
A connection for sending a connection destination information message indicating that the connection destination is the videophone terminal for the switching network to the IP videophone terminal in response to a call request for calling between the IP videophone terminal and the switching network videophone terminal Prior information notification means;
A gateway characterized by comprising switching network side image control information transmitting means for transmitting image control information to a switching network videophone terminal in response to a request from an IP videophone terminal. 5. The gateway according to claim 4, connected to an IP network and a circuit switching network, an IP videophone terminal connected to the gateway via the IP network, and an exchange connected to the gateway via the switching network An IP videophone terminal of a videophone system comprising a network videophone terminal,
The IP television telephone terminal comprises an image control request means for transmitting an image control request to the opposite switching network videophone terminal to the gateway in response to the connection destination information message. Phone terminal.

Images