JP2010177850A - Facsimile machine and facsimile communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid occurrence of communication abnormality due to packet loss in an IP network while making good use of an error retransmission protocol when performing facsimile transmission in a deemed voice system. <P>SOLUTION: A facsimile machine includes a facsimile communication unit 11 which performs communication control over G3 facsimile communication, and a packet control unit 12 which converts a procedure signal and an image signal output by the facsimile communication unit 11 into RTP packets and transmits the RTP packets to the IP network, and recovers the procedure signal and the image signal from RTP packets received from the IP network to output them to the facsimile communication unit 11. The packet control unit 12 transmits an RTP packet having the same data contents with an RTP packet based upon the image signal once when transmitting the RTP packet, performs retransmission processing for transmitting an RTP packet having the same data contents with an RTP packet based upon the procedure signal a plurality of times when transmitting the RTP packet, and performs reception packet processing for deeming that one RTP packet is received when the RTP packet having the same data contents is received several times. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a facsimile apparatus and a facsimile communication method for performing facsimile communication by an assumed voice method using an IP telephone service.

  Facsimile communication based on the assumed voice method is performed between G3 facsimiles that are assumed to be used on a public telephone network by using an IP telephone service. In the deemed voice method, a facsimile signal is regarded as a voice signal, and an analog voice signal is digitized before packet transmission. That is, in an IP phone, voice data is transmitted and received between terminals having IP addresses by a VoIP (Voice over IP) protocol or the like. In a facsimile communication using a deemed voice method, a facsimile procedure signal or image is transmitted using the VoIP technology. Signals (hereinafter referred to as PIX signals) are transmitted and received. Due to the nature of the IP network used by the IP telephone service, packets may be lost or delayed.

  In RTP (Real-Time Transport Protocol), which is a protocol normally used in IP telephone services, real-time performance is more important than communication reliability. Therefore, in RTP, even when a packet is lost, the packet is not retransmitted. Therefore, when performing a facsimile communication by the deemed voice method using the IP network, if a packet loss occurs, the facsimile signal may not be correctly transmitted to the opposite device. Also, depending on the lost packet, there may be a communication error.

  In Patent Document 1, when transmitting a packet, a plurality of the same packets are transmitted, and even if one packet is lost in the IP network, if another same packet can reach the opposite device, transmission / reception that can avoid the influence of this packet loss The system is described. In this specification, transmitting a plurality of the same packets, that is, retransmitting one or more packets is referred to as multiplexing the packets.

JP 2004-282538 A (paragraph 0122-0134)

  However, in the transmission / reception system described in Patent Document 1, when a plurality of the same packets are always transmitted, compared with the case where one packet is transmitted, the transmission side device and the reception side device require higher data processing capabilities. Is done. Further, in G3 facsimile, an error retransmission protocol called ECM (Error Correction Mode) is prepared, and when an error occurs during transmission of a PIX signal, it is retransmitted in the facsimile procedure. Therefore, the influence of packet loss can be avoided even if a plurality of packets are not transmitted during transmission of the PIX signal.

  Therefore, the present invention provides a facsimile apparatus and a facsimile that avoids the occurrence of communication abnormality due to packet loss in the IP network while utilizing the error retransmission protocol when performing facsimile transmission by the deemed voice method using the IP telephone service. An object is to provide a communication method.

  A facsimile apparatus according to the present invention includes a facsimile communication unit that performs communication control of G3 facsimile communication, a procedure signal and an image signal output from the facsimile communication unit, RTP-packetized and transmitted to the IP network, and an RTP received from the IP network. A packet control unit that restores the procedure signal and the image signal from the packet and outputs them to the facsimile communication unit. When transmitting the RTP packet based on the image signal, the packet control unit transmits the RTP packet having the same data contents once. When an RTP packet based on a procedure signal is transmitted, a retransmission process is performed in which an RTP packet having the same data content is transmitted a plurality of times. When an RTP packet having the same data content is received a plurality of times, it is considered that one RTP packet has been received. Receive packet processing is executed.

  A facsimile communication method according to the present invention is a facsimile communication method for transmitting and receiving RTP packets of image signals and procedure signals in the G3 facsimile communication system. When transmitting RTP packets based on image signals, 1 RTP packet having the same data content is transmitted. When the RTP packet based on the procedure signal is transmitted twice, the RTP packet with the same data content is transmitted a plurality of times, and one RTP packet is received when the RTP packet with the same data content is received a plurality of times. It is characterized by executing the received packet processing that is considered to have been performed.

  According to the present invention, it is possible to efficiently avoid the occurrence of communication abnormality due to packet loss in the IP network when performing facsimile transmission by the deemed voice method using the IP telephone service.

1 is a block diagram showing a configuration of a first embodiment of a facsimile apparatus according to the present invention. It is a sequence diagram which shows the communication procedure of IP telephone service. It is explanatory drawing which shows the structural example of a RTP packet. It is a sequence diagram for demonstrating the process which multiplexes an RTP packet. It is a flowchart which shows the transmission process of a RTP packet. It is a flowchart which shows the reception process of an RTP packet. It is explanatory drawing which shows an example of a sequence number management table. It is a sequence diagram which shows an example of the facsimile communication procedure which the facsimile apparatus shown by FIG. 1 performs. It is explanatory drawing which shows the format of the procedure signal NSF / CSI / DIS signal. It is explanatory drawing which shows the format of the procedure signal NSS / TSI / DCS signal. It is a sequence diagram which shows an example of the communication processing which the facsimile apparatus of 2nd Embodiment performs. It is explanatory drawing which shows an example of an INVITE message. It is explanatory drawing which shows an example of a 200OK message. It is a sequence diagram which shows an example of the communication process which the facsimile apparatus of 3rd Embodiment performs. 1 is a block diagram showing a main part of a facsimile apparatus according to the present invention.

Embodiment 1. FIG.
FIG. 1 is a block diagram showing a configuration of a first embodiment (Embodiment 1) of a facsimile apparatus according to the present invention. With reference to FIG. 1, the configuration of the facsimile apparatus of the first embodiment will be described.

  The control unit 101 controls each unit to realize a function as a network facsimile. The network control unit 102 controls an interface with the network 108. The data buffer 103 stores packet data transmitted to the network 108 and packet data received from the network 108.

  The audio CODEC 104 encodes an analog signal to be transmitted into a digital signal, and decodes the received digital signal into an analog signal. The FAX communication unit 105 controls G3 facsimile conforming to TTC (Information and Communication Technology Committee) standard JT-T30 (corresponding to ITU-T recommendation T30). The CNG detection unit 106 detects a CNG signal (Calling tone) transmitted from the opposite device and indicating a facsimile apparatus. The memory 107 stores information for managing the sequence number of the received RTP packet. The facsimile apparatus shown in FIG. 1 multiplexes and transmits RTP packets in communication using the IP telephone service.

  First, a general IP telephone service communication procedure will be described. FIG. 2 is a sequence diagram showing a communication procedure of the IP telephone service. A general communication process using the IP telephone service will be described with reference to FIG.

  When communication is started by the user performing a call operation (hereinafter referred to as dialing) on the calling side (step S201), the calling side transmits an INVITE message (step S202).

  When the receiving side receives the INVITE message, it returns a 100 TRYING message to the calling side and makes a provisional response to the request (step S203). Further, the receiving side rings a bell for calling the user (step S204), returns a 180 RINGING message to the calling side, and makes a provisional response (step S205). When the user hooks off on the incoming side (step S206), the incoming side returns a 200 OK message to the outgoing side (step S207).

  When receiving the 200 OK message, the calling side transmits an ACK message to the receiving side to notify that a response to the INVITE message has been received (step S208). When the processes of steps S201 to S208 are performed, a call is started between the users (step S209). The process in the area surrounded by the broken line shown in FIG. 2 indicates a process during a call.

  When a call is started, RTP packets generated by digitizing voice signals are transmitted at regular intervals on both the outgoing side and the incoming side. The transmission interval is usually 20 ms. FIG. 3 is an explanatory diagram illustrating a configuration example of an RTP packet. As shown in FIG. 3, the RTP packet is composed of an IP header 301, a UDP header 302, an RTP header 303, and code data 304. The RTP header 303 includes a sequence number 305. The sequence number 305 indicates the packet transmission order. For example, it is assumed that numbers 0 to n are assigned in order to each RTP packet.

  When the call ends and, for example, the user on the calling side hooks on (step S210), the calling side transmits a BYE message to the called side (step S211). The called party returns a 200 OK message in response to the BYE message (step S212), and the communication using the IP telephone service ends.

  FIG. 4 is a sequence diagram for explaining a process of multiplexing RTP packets. A process of multiplexing RTP packets will be described with reference to FIG.

  RTP packet multiplexing is performed during a call between the calling side and the called side (corresponding to step S209 shown in FIG. 2). Here, in particular, processing for multiplexing RTP packets transmitted from the calling side to the called side will be described.

  When the call is started, transmission of the RTP packet is started. First, the originating side transmits an RTP packet with sequence number 0 to the terminating side (step S401). In a general communication process, an RTP packet with sequence number 1 is transmitted after 20 ms, but in the example shown in FIG. 4, an RTP packet with sequence number 0 is transmitted before the RTP packet with sequence number 1 is transmitted. After 10 ms from the time, the RTP packet with sequence number 0 is retransmitted (step S402). The reason for shifting the transmission timing of the first RTP packet and the retransmission timing is that it is expected to reduce the probability of packet loss.

  In step S 401, when the receiving side receives the RTP packet with the sequence number 0, the packet data is received for the first time, so the RTP packet data with the sequence number 0 is stored in the data buffer 103. In step S402, when the called party receives the retransmitted RTP packet with sequence number 0, the retransmitted RTP packet is discarded because the RTP packet with sequence number 0 has already been received (step S403). Thereafter, as long as no packet loss occurs for the RTP packets with sequence numbers 1 to n transmitted before the call is terminated, the processes of steps S401 to S403 are repeated.

  Next, processing when packet loss occurs in the IP network will be described. As shown in FIG. 4, it is assumed that the RTP packet with the sequence number 2 is lost for some reason in the IP network (step S408). In this case, the RTP packet is not received by the receiving side, but the RTP packet of sequence number 2 is retransmitted from the calling side after 10 ms (step S409). When the receiving side receives the retransmitted RTP packet with sequence number 2, it stores it in the data buffer 103 because it is the first RTP packet with sequence number 2 received. That is, the packet loss that occurred in step S408 is avoided by the packet retransmission in step S409.

  FIG. 5 is a flowchart showing RTP packet transmission processing. With reference to FIG. 5, processing when the calling side transmits an RTP packet will be described.

  When a call is started between the calling side and the called side, the transmitting side of the RTP packet initializes the sequence number N (step S501) and transmits the RTP packet with the sequence number N (step S502). In step S502, when the RTP packet with the sequence number N is transmitted, it is determined whether or not to multiplex the packet (step S503). A method for determining whether to multiplex will be described later.

  If it is determined in step S503 that the data is not multiplexed, the process waits for 20 ms (step S504). After waiting for 20 ms, the sequence number N is incremented by 1 (step S505), and the process returns to step S502 to transmit the next RTP packet.

  If it is determined in step S503 that multiplexing is to be performed, the process waits for 10 ms (step S506). After waiting for 10 ms, the RTP packet with the sequence number N is retransmitted (step S507). Thereafter, the sequence number N is incremented by 1 (step S508) and waits for 10 ms (step S509). After waiting for 10 ms, the process returns to step S502 to transmit the next RTP packet.

  Steps S502 to S509 are repeated until the call between the caller and the callee is completed.

  FIG. 6 is a flowchart showing the RTP packet reception process. With reference to FIG. 6, a process when the called party receives an RTP packet will be described.

  When a packet is received from the transmission side (step S601), the reception side checks whether the sequence number of the received packet is a sequence number that has already been received (step S602). FIG. 7 is an explanatory diagram showing an example of a sequence number management table. The sequence number management table is a table in which a sequence number and a received flag indicating whether or not a packet having the sequence number has been received are set. In the sequence number management table, when the received flag is 0, it indicates that a packet having the corresponding sequence number has not been received yet. When the received flag is 1, the packet having the corresponding sequence number Indicates that has already been received. In step S602, whether or not the sequence number of the received packet has already been received is confirmed with reference to the sequence number management table shown in FIG.

  If the sequence number of the received packet has already been received in step S602, the received packet is determined to be unnecessary and discarded (step S603). Then, it returns to step S601 and waits for reception of the next packet from the transmission side.

  If the sequence number of the received packet has not been received in step S602, the received packet is stored in the data buffer 103 (step S604). Then, the received flag for the sequence number in the sequence number management table is updated to 1 (step S605). Then, it returns to step S601 and waits for reception of the next packet from the transmission side.

  FIG. 8 is a sequence diagram showing an example of a facsimile communication procedure performed by the facsimile apparatus shown in FIG. With reference to FIG. 8, the process of the facsimile communication procedure performed by the facsimile apparatus shown in FIG. 1 will be described.

  When facsimile communication based on the assumed voice method is performed using the IP network, the processing shown in the sequence diagram of FIG. 8 is performed. These processes are executed as a process during a call between the calling side and the called side shown in FIG. 2 (corresponding to step S209 shown in FIG. 2). Note that the processing signals included in the broken line range shown in FIG. 8 are collectively referred to as procedure signals. The facsimile apparatus of this embodiment multiplexes RTP packets including procedure signals.

  First, a CNG signal indicating that the FAX communication unit 105 on the facsimile data transmission side (calling side) is a facsimile apparatus via the voice CODEC 104, the data buffer 103, and the network control unit 102, The data is transmitted to the receiving side (referred to as the receiving side) (step S801). As shown in FIG. 1, the analog signal output from the FAX communication unit 105 is converted into a digital signal by the voice CODEC 104 and stored in the data buffer 103, and the network control unit 102 is stored in the data buffer 103. The digital signal is converted into an RTP packet and sent to the network 108. On the receiving side, when the CNG signal is detected by the CNG detecting unit 1006, the FAX communication unit 105 transmits a CED signal (called terminal identification signal) via the voice CODEC 104, the data buffer 103, and the network control unit 102. (Step S802).

  Further, on the receiving side, the FAX communication unit 105 transmits an NSF / CSI / DIS signal to the calling side via the voice CODEC 104, the data buffer 103, and the network control unit 102 (step S803). FIG. 9 is an explanatory diagram showing the format of the procedure signal NSF / CSI / DIS signal. The NSF 901 (NSF signal) is a signal called a non-standard function identification signal, and includes information for notifying the calling side of the capability of the called side. CSI 902 (CSI signal) is a signal called a called terminal identification signal and includes identification information on the called side. DIS903 (DIS signal) is a signal called a digital identification signal, and indicates that the receiving side has a function conforming to T30. As shown in FIG. 9, a packet multiplexing function presence / absence bit 904 is set in the NSF 901. The packet multiplexing function presence / absence bit 904 indicates the presence / absence of the packet multiplexing function. If the packet multiplexing function is present, the bit is valid. In step S803, when the NSF / CSI / DIS signal is transmitted, the receiving side enables the packet multiplexing function presence / absence bit 904 of the NSF 901. The packet multiplexing function is a retransmission process in which RTP packets having the same data contents are transmitted a plurality of times when an RTP packet based on a procedure signal is transmitted, and one RTP when an RTP packet having the same data contents is received a plurality of times. This is a function for executing received packet processing that considers that a packet has been received.

  On the transmission side, the FAX communication unit 105 receives the NSF / CSI / DIS signal from the reception side via the network control unit 102, the data buffer 103, and the voice CODEC 104. Note that the network control unit 102 extracts data that is a digital signal from the RTP packet received via the network 108 and outputs the data to the voice CODEC 104 via the data buffer 103. The voice CODEC 104 converts data that is a digital signal into an analog signal (in this case, an NSF signal, a CSI signal, and a DIS signal) and outputs the analog signal to the FAX communication unit 105. The FAX communication unit 105 checks the packet multiplexing function presence / absence bit 904 in the NSF signal, and if it is valid, requests the network control unit 102 to start multiplexing of the RTP packet. In response to the request, the network control unit 102 starts multiplexing of RTP packets (step S804). Thereafter, the network control unit 102 executes the processes of steps S506 to S509 shown in FIG.

  On the transmitting side, the FAX communication unit 105 transmits an NSS / TSI / DCS signal to the receiving side via the voice CODEC 104, the data buffer 103, and the network control unit 102 (step S805). FIG. 10 is an explanatory diagram showing the format of the procedure signal NSS / TSI / DCS signal. NSS 1001 (NSS signal) is a signal called a non-standard function setting signal, and includes information determined based on capability information on the called side presented in the NSF signal from the called side. The TSI 1002 (TSI signal) is a signal called a transmission terminal identification signal and includes identification information of a transmission station. The DCS 1003 (DCS signal) is a signal called a digital command signal, and commands function setting in response to the standard function indicated by the DIS 903. As illustrated in FIG. 10, the FAX communication unit 105 sets a packet multiplexing function presence / absence bit 1004 in the NSS 1001. The function of the packet multiplexing function presence / absence bit 1004 is the same as that of the packet multiplexing function 904. In step S805, when transmitting the NSS / TSI / DCS signal, the transmission side validates the packet multiplexing function presence / absence bit 1004 of the NSS 1001.

  On the incoming side, the FAX communication unit 105 receives the NSS / TSI / DCS signal from the outgoing side via the network control unit 102, the data buffer 103, and the voice CODEC 104. The FAX communication unit 105 checks the packet multiplexing function presence / absence bit 1004 in the NSS signal, and if it is valid, requests the network control unit 102 to start multiplexing of the RTP packet. In response to the request, the network control unit 102 starts multiplexing of RTP packets (step S806). Thereafter, the network control unit 102 executes the processes of steps S506 to S509 shown in FIG.

  On the transmission side, after the RTP packet multiplexing is started in step S804, the FAX communication unit 105 can use the channel at a predetermined transmission rate via the voice CODEC 104, the data buffer 103, and the network control unit 102. A TCF signal for performing a training check is transmitted (step S807). On the receiving side, the FAX communication unit 105 transmits a CFR signal, which is a reception preparation confirmation signal indicating that the message transmission may be started, via the voice CODEC 104, the data buffer 103, and the network control unit 102 (step). S808). When the FAX communication unit 105 receives the CFR signal from the receiving side via the network control unit 102, the data buffer 103, and the voice CODEC 104 on the transmission side, the multiplexing of the RTP packet is completed for the network control unit 102. Ask to do. The network control unit 102 stops multiplexing of RTP packets in response to the request (step S809).

  In step S809, after receiving the CFR signal and stopping the multiplexing of the RTP packet, the FAX communication unit 105 transmits the PIX signal via the voice CODEC 104, the data buffer 103, and the network control unit 102 on the transmission side. (Step S810). The reason why the PIX signal is transmitted after the multiplexing of the RTP packet is stopped is that the facsimile apparatus has an error retransmission protocol called ECM (Error Correction Mode) for the PIX signal. That is, even if a failure that causes packet loss occurs, it is possible to avoid the packet loss by the error retransmission protocol, and it is not necessary to multiplex packets (packet retransmission). Further, during the transmission of the PIX signal, more data is transmitted, and thus higher data processing capability is required. However, by stopping the packet multiplexing, the data processing load in the facsimile apparatus is reduced. Effect is also obtained.

  When the transmission of the PIX signal is completed, the FAX communication unit 105 requests the network control unit 102 to resume multiplexing of the RTP packet on the transmission side. In response to the request, the network control unit 102 resumes multiplexing of the RTP packet (step S811) and transmits a procedure signal. The transmission side transmits an EOP signal that is a procedure end signal (step S812). When the receiving side receives the EOP signal, it returns an MCF signal as a message confirmation signal indicating affirmation to the EOP signal (step S813). Finally, the transmission side transmits a DCN signal indicating a line disconnection command, and the procedure signal ends.

  Such a facsimile apparatus can avoid occurrence of communication abnormality due to packet loss in the IP network by multiplexing RTP packets. In addition, since the RTP packet is multiplexed only in the facsimile procedure signal portion, the data processing load in the facsimile apparatus can be reduced.

Embodiment 2. FIG.
A second embodiment (embodiment 2) of the facsimile apparatus according to the present invention will be described. The configuration of the facsimile apparatus of the second embodiment is the same as that of the facsimile apparatus of the first embodiment shown in FIG. However, unlike the facsimile apparatus of the first embodiment that sets the packet multiplexing function presence / absence bit in the NSF signal and the NSS signal, the facsimile apparatus of the second embodiment does not include the packet multiplexing function presence / absence bit in the INVITE message. Set.

  FIG. 11 is a sequence diagram illustrating an example of communication processing performed by the facsimile apparatus according to the second embodiment. With reference to FIG. 11, a description will be given of a process in which the facsimile apparatus of the second embodiment recognizes the presence / absence of a packet multiplexing function.

  When the user dials on the calling side and IP telephone communication is started (step S1101), the network control unit 102 on the calling side transmits an INVITE message (step S1102). The facsimile apparatus sets information indicating the presence / absence of an RTP packet multiplexing function in the INVITE message.

  FIG. 12 is an explanatory diagram showing an example of the INVITE message. As shown in FIG. 12, the INVITE message includes an SDP (Session Description Protocol) 1201 that is a protocol for describing an initial setting value. In this SDP 1201, a packet multiplexing function presence / absence bit (information indicating the presence / absence of the RTP packet multiplexing function) 1202 is set. The packet multiplexing function presence / absence bit 1202 indicates the presence / absence of the packet multiplexing function, and if the packet multiplexing function is provided, the bit is valid.

  When the network control unit 102 on the receiving side receives the INVITE message, the control unit 101 reads the packet multiplexing function presence / absence bit 1202 in the SDP 1201 of the INVITE message, and the opposite device (outgoing side) has the RTP packet multiplexing function. It recognizes that it has (step S1103). Then, the network control unit 102 on the receiving side returns a 100 TRYING message to the calling side and makes a provisional response to the request (step S1104). Further, the control unit 101 on the receiving side rings a bell for calling the user (step S1105), and the network control unit 102 returns a 180 RINGING message to the calling side and makes a provisional response (step S1106). When the user hooks off at the incoming side (step S1107), the incoming side network control unit 102 returns a 200 OK message to the outgoing side (step S1108).

  FIG. 13 is an explanatory diagram showing an example of a 200 OK message. As shown in FIG. 13, the 200 OK message includes an SDP 1301. The SDP 1301 is determined based on the setting value of the calling side presented by the SDP 1201 in the INVITE message notified from the calling side. Therefore, the packet multiplexing function presence / absence bit 1302 is set in the SDP 1301. The packet multiplexing function presence / absence bit 1302 enables the bit when the called side has a packet multiplexing function. In step S1108, the packet multiplexing function presence / absence bit 1302 is valid.

  When receiving the 200 OK message, the network control unit 102 on the transmission side reads the packet multiplexing function presence / absence bit 1302 in the SDP 1301 of the 200 OK message, and the opposite device (incoming side) has the RTP packet multiplexing function. (Step S1109). Thereafter, when facsimile communication is started, the network control unit 102 multiplexes RTP packets in the procedure signal portion. When receiving the CFR signal, the FAX communication unit 105 notifies the network control unit 102 that the PIX signal is transmitted before outputting the PIX signal. The network control unit 102 ends the multiplexing of the RTP packet in response to the notification. Further, when the transmission of the PIX signal is completed, the FAX communication unit 105 notifies the network control unit 102 that the transmission of the PIX signal is completed before outputting the EOP signal. The network control unit 102 resumes multiplexing of the RTP packet in response to the notification.

  Such a facsimile apparatus can start multiplexing of RTP packets after recognizing whether or not the opposite apparatus has an RTP packet multiplexing function. When the opposite device does not have the RTP packet multiplexing function, that is, when the packet receiving side does not manage the sequence number, the multiplexed RTP packet is unconditionally received on the receiving side. May be stored in the data buffer. As a result, overflow of the data buffer is caused, and further, there is a possibility that packet loss due to the overflow occurs to deteriorate the communication performance. Therefore, it is possible to avoid overflow of the data buffer of the opposite device by starting the multiplexing of the RTP packet after confirming whether or not the opposite device has the RTP packet multiplexing function.

  In addition, since it is possible to recognize whether the opposite device has the RTP packet multiplexing function before the facsimile communication is started, whether or not the RTP packet multiplexing function is provided after the facsimile communication is started is determined. Rather than recognizing, it is possible to suppress the load concentration in information processing.

  The setting of the packet multiplexing function presence / absence bit is not limited to the SDP of the INVITE message, and may be set to other messages and signals as long as the original communication processing is not hindered.

Embodiment 3. FIG.
A third embodiment (embodiment 3) of the facsimile machine according to the present invention will be described. The configuration of the facsimile apparatus of the third embodiment is the same as the configuration of the facsimile apparatus of the first embodiment shown in FIG. However, unlike the case where the facsimile apparatus of the first embodiment sets the packet multiplexing function presence / absence bit in the NSF signal and the NSS signal, the facsimile apparatus of the third embodiment does not proceed to the facsimile communication procedure. A sequence for confirming the presence or absence of an RTP packet multiplexing function using a PB (Push Button) signal, that is, a DTMF (Dial Tone Multi Frequency) signal is provided. Note that the facsimile apparatus of the third embodiment includes PB signal receiving means (frequency determination means for received signals).

  FIG. 14 is a sequence diagram illustrating an example of communication processing performed by the facsimile apparatus according to the third embodiment. With reference to FIG. 14, a description will be given of a process in which the facsimile apparatus of the third embodiment recognizes the presence or absence of a packet multiplexing function.

  The facsimile apparatus performs processing for confirming whether or not the counterpart device has the RTP packet multiplexing function using the PB signal (step S1401), and then performs processing of the facsimile communication procedure (step S1402). .

  A process in which the facsimile apparatus confirms whether or not the opposite apparatus has an RTP packet multiplexing function using the PB signal will be described in detail. First, the FAX communication unit 105 on the transmission side transmits an RTP packet multiplexing request to the call reception side using a predetermined PB signal via the voice CODEC 104, the data buffer 103, and the network control unit 102 (step S1403). . When the FAX communication unit 105 receives a PB signal via the voice CODEC 104, the data buffer 103, and the network control unit 102 on the receiving side, the received PB signal is a PB signal that requests RTP packet multiplexing processing. Judge whether there is. When it is determined that the signal is a PB signal requesting RTP packet multiplexing processing and has a packet multiplexing function, the FAX communication unit 105 passes through the voice CODEC 104, the data buffer 103, and the network control unit 102. A predetermined PB signal indicating that the request for RTP packet multiplexing is accepted (PB signal indicating that the packet multiplexing function is provided) is returned (step S1404). Further, the FAX communication unit 105 requests the network control unit 102 to start multiplexing of RTP packets. In response to the request, the network control unit 102 starts multiplexing of RTP packets (step S1405). When the FAX communication unit 105 receives a PB signal via the voice CODEC 104, the data buffer 103, and the network control unit 102 on the transmission side, it indicates that the received PB signal accepts the RTP packet multiplexing request. It is determined whether or not the PB signal is a predetermined PB signal. If the FAX communication unit 105 determines that the signal is such a PB signal, the FAX communication unit 105 starts multiplexing the RTP packet to the network control unit 102. Ask that. In response to the request, the network control unit 102 starts multiplexing of RTP packets (step S1406).

  By the operations in steps S1405 and S1406, the facsimile apparatus can confirm that the opposite machine has the RTP packet multiplexing function and start multiplexing the RTP packets. Thereafter, the facsimile apparatus proceeds to a facsimile communication procedure process (step S1402). When receiving the CFR signal, the FAX communication unit 105 notifies the network control unit 102 that the PIX signal is transmitted before outputting the PIX signal. The network control unit 102 ends the multiplexing of the RTP packet in response to the notification. Further, when the transmission of the PIX signal is completed, the FAX communication unit 105 notifies the network control unit 102 that the transmission of the PIX signal is completed before outputting the EOP signal. The network control unit 102 resumes multiplexing of the RTP packet in response to the notification.

  Such a facsimile apparatus has an advantage that it is not necessary to newly set a dedicated bit or the like because the presence or absence of an RTP packet multiplexing function can be confirmed using a predetermined PB signal. In addition, since the presence or absence of the RTP packet multiplexing function can be determined before starting the facsimile communication procedure, it is possible to suppress the concentration of load in information processing.

  In each of the above embodiments, the network control unit 102, the data buffer 103, and the voice CODEC 104 are components of the facsimile apparatus. However, the network control unit 102, the data buffer 103, and the voice CODEC 104 are replaced with the FAX communication unit 105. It may be realized as a component of a device connected to a facsimile machine equipped with the above. For example, the network control unit 102, the data buffer 103, and the voice CODEC 104 may be realized as a VoIP adapter.

  FIG. 15 is a block diagram showing the main part of the facsimile apparatus according to the present invention. As shown in FIG. 15, the facsimile apparatus 1 includes a facsimile communication unit 11 (corresponding to the FAX communication unit 105 shown in FIG. 1) that performs communication control of G3 facsimile communication, and a procedure signal and an image signal output from the facsimile communication unit 11. Is converted into RTP packets, transmitted to the IP network, the procedure signal and the image signal are restored from the RTP packet received from the IP network, and output to the facsimile communication unit 11 (the network control unit 102 shown in FIG. 1). The packet control unit 12 transmits an RTP packet having the same data content once when transmitting an RTP packet based on an image signal, and transmits the same data when transmitting an RTP packet based on a procedure signal. Execute resend process to send RTP packet of contents multiple times, same It is configured to execute the received packet processing considered to have received a single RTP packet when receiving a plurality of times an RTP packet over data contents.

  In addition, as the facsimile communication apparatus of each of the above embodiments, the following facsimile communication apparatuses are also disclosed (1) to (4).

(1) Information indicating that it is possible to execute retransmission processing and reception packet processing on a procedure signal (for example, NSF signal) input by the facsimile communication unit (for example, a packet multiplexing function that is set to be valid) The presence / absence bit 904) is included, and executable information determination means (for example, included in the FAX communication unit 105 shown in FIG. 1) is provided. The packet control unit includes the executable information determination means as the procedure signal. A facsimile communication apparatus that executes a retransmission process when an RTP packet based on a procedure signal is transmitted when it is determined that the possible information is included.

(2) Possibility information (for example, packet multiplexing function presence / absence bit 1302 set to be valid) indicating that retransmission processing and reception packet processing can be performed on the final response message (for example, 200 OK) for the INVITE message ) Is included in the executable information determination means (for example, included in the network control section 102 shown in FIG. 1), and the packet control section enables the executable information determination means to be the final response message. A facsimile communication apparatus that executes a retransmission process when transmitting an RTP packet based on a procedure signal when it is determined that information is included.

(3) A DTMF signal transmission / reception unit (for example, included in the FAX communication unit 105 shown in FIG. 1) that outputs a DTMF signal to the packet control unit and receives the DTMF signal via the packet control unit, and a DTMF signal transmission / reception unit DTMF signal determination unit that determines whether or not the DTMF signal received is a specific signal indicating that retransmission processing and reception packet processing can be executed (for example, in the FAX communication unit 105 shown in FIG. 1) The packet control unit transmits the RTP packet based on the procedure signal when the DTMF signal determination unit determines that the DTMF signal received by the DTMF signal transmission / reception unit is a specific signal. A facsimile communication apparatus that executes retransmission processing.

(4) A facsimile communication apparatus in which the packet control unit stops executing retransmission processing when transmitting an RTP packet based on an image signal, and resumes retransmission processing when transmission of the RTP packet based on the image signal is completed.

DESCRIPTION OF SYMBOLS 1 Facsimile apparatus 11 Facsimile communication part 12 Packet control part 101 Control part 102 Network control part 103 Data buffer 104 Voice CODEC
105 FAX Communication Unit 106 CNG Detection Unit 107 Memory 108 Network 301 IP Header 302 UDP Header 303 RTP Header 304 Code Data 305 Sequence Number 901 NSF
902 CSI
903 DIS
904, 1004, 1202, 1302 Packet multiplexing function presence / absence bit 1001 NSS
1002 TSI
1003 DCS
1201, 1301 SDP

Claims (7)

A facsimile communication unit that performs communication control of G3 facsimile communication;
Packets that are converted into RTP packets for the procedure signal and image signal output from the facsimile communication unit and transmitted to the IP network, and that the procedure signal and image signal are restored from the RTP packet received from the IP network and output to the facsimile communication unit A control unit,
The packet control unit
When transmitting an RTP packet based on an image signal, an RTP packet having the same data content is transmitted once. When an RTP packet based on a procedure signal is transmitted, an RTP packet having the same data content is transmitted a plurality of times.
A facsimile apparatus characterized by executing reception packet processing that considers that one RTP packet is received when RTP packets having the same data contents are received a plurality of times. An executable information determination means for determining whether or not the procedure signal input by the facsimile communication unit includes possible information indicating that retransmission processing and reception packet processing can be performed;
2. The facsimile according to claim 1, wherein the packet control unit executes a retransmission process when transmitting the RTP packet based on the procedure signal when the executable information determination unit determines that the procedure information includes the capability information. apparatus. An executable information determination unit that determines whether or not the final response message for the INVITE message includes possible information indicating that retransmission processing and reception packet processing can be performed;
The packet control unit executes a retransmission process when transmitting an RTP packet based on a procedure signal when the executable information determining unit determines that the executable information is included in a final response message. Facsimile device. A DTMF signal transmitting / receiving unit that outputs a DTMF signal to the packet control unit and receives the DTMF signal via the packet control unit;
A DTMF signal determination unit that determines whether or not the DTMF signal received by the DTMF signal transmission / reception unit is a specific signal indicating that retransmission processing and reception packet processing can be performed;
When the DTMF signal determination unit determines that the DTMF signal received by the DTMF signal transmission / reception unit is the specific signal, the packet control unit executes a retransmission process when transmitting an RTP packet based on the procedure signal The facsimile apparatus according to claim 1. The packet control unit stops executing retransmission processing when transmitting an RTP packet based on an image signal, and restarts retransmission processing when transmission of the RTP packet based on the image signal is completed. The facsimile apparatus according to any one of the above. A facsimile communication method for transmitting and receiving RTP packetized image signals and procedure signals in a G3 facsimile communication system,
When transmitting an RTP packet based on an image signal, an RTP packet having the same data content is transmitted once. When an RTP packet based on a procedure signal is transmitted, an RTP packet having the same data content is transmitted a plurality of times.
A facsimile communication method characterized in that when an RTP packet having the same data content is received a plurality of times, a received packet process is performed in which one RTP packet is regarded as received. Stop the retransmission process when sending RTP packets based on image signals,
The facsimile communication method according to claim 6, wherein the retransmission process is resumed when transmission of the RTP packet based on the image signal is completed.

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