JP4075896B2 - Image communication device - Google Patents

Description

  The present invention relates to an image communication apparatus that transmits and receives image data using a call control protocol such as SIP (Session Initiation Protocol).

  In recent years, an IP facsimile apparatus that establishes a media session by SIP and transmits and receives image data has been proposed (see, for example, Patent Documents 1 to 3). Text-based signaling messages are exchanged between the calling device and the called device to establish a media session. In the exchange of signaling messages, the media type, codec, IP address, port number, etc. employed in the media session are negotiated. Normally, information on these media sessions is described by SDP (Session Description Protocol).

JP 2004-172853 A JP 2004-221945 A JP 2004-260535 A

  Originally, the SIP server is responsible for call control and is not involved in the contents of the media session or the description contents by SDP. However, since IP facsimile machines that transmit and receive image data using SIP have not yet become widespread, the carrier (communication carrier) SIP server is implemented only on the basis of voice calls using IP phones. There are many things. In other words, the carrier's SIP server accepts call control processing only for those whose specific contents are described in SDP, and accepts call control processing for request messages etc. whose specific contents are not described in SDP. There are many things that are not. For example, when the carrier's SIP server is intended for call control processing only for which “m = audio 5004 RTP / AVP0” is described by SDP, an IP facsimile machine may be installed in the carrier network. A request message describing a communication request for image data by SDP is rejected by the SIP server. For this reason, the problem that the media session for transmitting image data with an other party cannot be established arises.

  The present invention has been made in view of the above-mentioned problems, and even if the server that controls call control imposes restrictions on the description contents of the SDP, it is free to contact the other party without being restricted. An image communication apparatus that can negotiate the contents of a media session and can communicate image data using a call control protocol even when the apparatus is connected to a carrier network that is premised on the use of voice communication. The purpose is to provide.

  The image communication apparatus according to claim 1 is an image communication apparatus that establishes a media session and transmits image data by exchanging a message of a call control protocol with a counterpart, and is adapted to a carrier server to which the apparatus is connected. Storage means for storing the SDP header format to be transmitted, first description means for describing the SDP header of the request message to be transmitted in accordance with the SDP header format stored by the storage means, and a predetermined location where the server is not involved in the request message And a second description means for describing information relating to the media session actually requested from the other party.

  The image communication apparatus according to claim 2 is the image communication apparatus according to claim 1, wherein the second description unit describes information related to the media session in an SDP header described by the first description unit. It is characterized by a specific field.

The image communication apparatus according to claim 3 receives a request message described according to an SDP header format in an image communication apparatus that establishes a media session and receives image data by exchanging a call control protocol message with a partner. and it is characterized in that it comprises means for employing the information server is described at a predetermined position which is not involved in charge of call control as information about the media session partner is requested in the said request message received.

  The image communication apparatus according to claim 4 is the image communication apparatus according to claim 3, wherein the predetermined part not involved in the server is a specific field of an SDP header in the received request message. Yes.

  According to the image communication device according to claim 1 and the image communication device according to claim 3, even if the server that controls the call control imposes a restriction on the description content of the SDP, the restriction is not imposed. You can freely decide the contents of the media session. Thus, even when the image communication apparatus according to claim 1 is connected to a carrier network that is premised on only a specific media type, for example, use of voice communication, a media session is established with the other party to transmit / receive image data. It can be performed.

  According to the image communication apparatus according to claim 2 and the image communication apparatus according to claim 4, information relating to the media session that is actually requested of the other party is described in a specific field of the SDP header not involving the server that performs call control. Therefore, even if a request message in which the information is described is transmitted, the call control performed by the server is not adversely affected.

  Hereinafter, as an image communication apparatus according to an embodiment of the present invention, an IP facsimile communication function for transmitting and receiving image data of a document using a call control protocol, a G3 facsimile communication function, and the various types according to a request from a client apparatus A description will be given by taking as an example a multifunction machine type facsimile apparatus having a facsimile server function for performing facsimile communication.

  FIG. 1 shows a configuration example of the facsimile machine 1. That is, the facsimile apparatus 1 includes a CPU (Central Processing Unit) 2, a ROM (Read Only Memory) 3, a RAM (Random Access Memory) 4, an image memory 5, a modem 6, an NCU 7, a codec 8, a reading unit 9, and a recording unit 10. , A display unit 11, an operation unit 12, and a LAN interface 13, and the units 2 to 13 are connected by a bus 14.

  The CPU 2 functions as a control unit that controls each part of the facsimile apparatus 1 according to a control program stored in the ROM 3. The RAM 4 functions as a main memory and work area for the CPU 2. The RAM 4 stores a table X described later. The image memory 5 stores image data compressed and encoded by the codec 8.

  The modem 6 is, for example, an ITU-T (International Telecommunication Union) recommendation V.3. Modulate and demodulate transmitted / received data according to the 34 standard or the like. The NCU 7 is a line network control device that performs operations for closing and opening a line with the PSTN (Public Switched Telephone Network) 15, and connects the modem 6 to the PSTN 15 during G3 facsimile transmission / reception. The codec 8 compresses and encodes image data by JPEG method or MH, MR, MMR method or the like, and decodes received image data or the like, for facsimile transmission or the like.

  The reading unit 9 reads image data of a document, and includes, for example, a CCD color line image sensor, an A / D converter, an image processing circuit, and the like. The recording unit 10 takes out the recording paper from the paper feed cassette and records the image data on the recording paper. The display unit 11 includes, for example, an LCD (Liquid Crystal Display) arranged in parallel with the operation unit 12 and displays various screen information. The operation unit 12 includes various operation keys such as a start key, a character input key, and a function key, and various operations by the user are performed in the operation unit 12.

  The LAN interface 14 is an interface for connecting the facsimile machine 1 and a LAN (local area network) 16, and through this, the facsimile machine 1 is also used for an IP facsimile machine 17 or a router that implements a call control protocol or the like connected to the LAN 16. 18, image data can be transmitted and received after establishing a media session by SIP with the IP facsimile machine 17 on the IP network 19.

  The facsimile apparatus 1 having the above configuration implements a media session by SIP by implementing TCP / IP (Transmission Control Protocol / Internet Protocol), SIP, RTP (Real-time Transport Protocol), SDP (Session Description Protocol), and the like. Once established, it implements a function to send and receive image data to and from the other party. In the present embodiment, SIP will be described as an example of a call control protocol, but a text-based request and response message is exchanged with the other party prior to establishing a media session. Of course, it is possible to apply a call control protocol other than SIP as long as it exchanges information about the media session.

  The facsimile apparatus 1 having the above configuration and communication function stores, in the RAM 4, information indicating whether or not the SDP header format is limited for each carrier and an SDP header format that is compatible with the SIP server of the limited carrier. . Specifically, as shown in the table X of FIG. 2, for example, “restricted” or “unrestricted” is stored as information indicating whether or not there is a restriction on the SDP header format. Furthermore, as an SDP header format suitable for the SIP server of each carrier, for example, “v = *, o = *, s = *, c = IN IP4 *, t = *, m = audio 5004 RTP / AVP 0, a = rtpmap: 0 PCMU / 8000 "or the like is stored for each carrier. Here, “*” is information indicating that the description content is not restricted.

  In the present embodiment, information relating to a media session that is actually requested or responded to the other party is described in a specific field not involving the SIP server, for example, the “s” field. It should be noted that the presence or absence of restrictions on the SDP header format and the SDP header format to which the carrier's SIP server is compatible can be ascertained from the specifications provided by the carrier (communication carrier). Information in the table X is registered in advance when the facsimile apparatus 1 is shipped from the factory, or is registered by a predetermined operation of the user of the facsimile apparatus 1 or the like.

  The facsimile apparatus 1 further includes means for setting a carrier to which the apparatus 1 is connected among the carriers stored in the table X by a predetermined operation of the operation unit 12 or the like. When any carrier, for example, “telecom carrier B” is set as a carrier to which the apparatus is connected, the facsimile apparatus 1 uses the “communication carrier B” in the table X when transmitting / receiving image data using SIP. The SDP header in the signaling message is described in accordance with the SDP header format registered in association with the SDP header, and the medium that actually requests or responds to the other party in the “s” field that does not involve the SIP server in the SDP header. Describes information about the session.

  Next, processing operations executed when the facsimile apparatus 1 having the above-described configuration and communication function establishes a media session by SIP and transmits / receives image data are shown in the sequence diagram shown in FIG. 3, FIG. 4 and FIG. This will be described based on the flowchart shown in FIG. The processing operation of the facsimile apparatus 1 described based on these drawings is executed in accordance with a command issued by the CPU 2 as the control means based on the control program stored in the ROM 3. For convenience of explanation below, the facsimile machine 1 serving as the calling side is referred to as “calling side apparatus 1A”, and the facsimile machine 1 serving as the called side is referred to as “calling side apparatus 1B”.

  When the operation unit 12 or the like of the facsimile apparatus 1 (calling apparatus 1A) is instructed to transmit image data using SIP or other image data not using SIP (S1), SIP is used. When image data is transmitted by other communication that is not performed (S2: NO), image data transmission processing is performed by the communication, for example, G3 facsimile (S3).

  When transmitting image data using SIP (S2: YES), the calling-side apparatus 1A uses a table as to whether or not the SIP server 20 of the directly connected carrier imposes restrictions on the SDP header format. Judgment is made based on the information registered in X (S4). For example, as shown in Table X, if there is no restriction on the contents of the description because “*” is registered for all fields, the directly connected SIP server 20 restricts the SDP header format. A request message “INVITE” in which information related to the media session actually requested from the other party is described according to the SDP description rule is generated and transmitted to the other party (S5). That is, the calling-side apparatus 1A describes information on the media session requested from the other party in the fields “m” and “a” of the SDP header, and the fields “v”, “s”, “t”, etc. of the SDP header. In a field that is not normally used in SIP, information related to the media session is not described.

  On the other hand, when the SIP server 20 to which the calling side device 1A is directly connected determines that the restriction is imposed on the SDP header format (S4: YES), it is set as the carrier to which the own device 1A is connected. According to the SDP header format stored in the table X in association with the carrier, for example, as shown in FIG. 3, the SDP header is described in the request message “INVITE” (S6), and the media session actually requested from the other party is related. Information is described in the “s” field that does not involve the SIP server in the SDP header (S7). After the processing operation of S5 or S7, the generated request message “INVITE” is transmitted to the other party (S8, T1). Note that “FAX” described in the “s” field of the SDP header described in the request message M shown in FIG. 3 designates image data communication as a media type.

  The request message “INVITE” sent from the calling device 1A as described above is received by the SIP server 20 of the carrier. When the SIP server 20 imposes a restriction on the SDP header format, it is determined whether or not the SDP header in the request message conforms to a specific format requested by the SIP server, and conforms to the format. If so, the request message is transferred to the partner side (T2). On the other hand, if it does not conform to the format, an error message is returned to the calling side apparatus 1A, and no transfer to the other party side is performed.

  If the calling side device 1A that has transmitted “INVITE” in S8 does not receive a response message from the called side device 1B that is the counterpart, but receives an error message from the SIP server 20 (S9: NO), Predetermined call error processing is performed (S10). For example, the SIP server 20 such as recording communication error information in a log file or “Check if the set communication carrier matches the communication carrier to which the device is connected.” The display unit 11 displays a character string for notifying the user that it has not passed, or the recording unit 10 prints out the character string.

  When the called-side device 1B receives the request message “INVITE” sent from the calling-side device 1A in S8 through the SIP server 20 (S101: YES), the called-side device 1B includes the SDP header in the received request message “INVITE”. It is determined whether or not information related to the media session is described in the “s” field, which is a predetermined location not involving the SIP server (S102). In the “s” field, information on the media session, for example, information “FAX” indicating the media type, information “TCP” indicating UDP / TCP, and information “6109” indicating the port number, as shown in FIG. If it is described, it is determined that information related to the media session is described (S102: YES), and this is adopted as information related to the media session requested by the calling device 1A. The information described in the fields “m”, “a”, etc. of the SDP header in which information is to be described is discarded without being adopted (S103).

  On the other hand, when it is determined that the information about the media session is not described in the “s” field of the SDP header of the request message received by the called device 1B (S102: NO), the fields “m”, “ The information described in “a” and the like is adopted as information related to the media session requested by the calling device 1A (S104).

  Next, the called device 1B determines whether or not the SIP server 20 of the carrier to which the own device 1B is directly connected imposes a restriction on the SDP header format based on the information registered in the table X ( S105). When the directly connected SIP server 20 determines that there is no restriction on the SDP header format (S5: NO), information related to the media session that actually responds to the calling device 1A is described in accordance with the SDP description conventions. A response message “200 OK” is generated and transmitted to the calling device 1A (S106). That is, the called side device 1B describes information on the media session responding to the calling side device 1A in the fields “m” and “a” of the SDP header, and the fields “v”, “s”, “ Information relating to the media session is not described in a field that is not normally used in SIP, such as “t”.

  On the other hand, when the SIP server 20 to which the called apparatus 1B is directly connected determines that the SDP header format is restricted (S105: YES), the carrier set as the carrier to which the own apparatus 1B is connected The SDP header of the response message “200 OK” is described in accordance with the SDP header format stored in association with the table X (S107), and information on the media session that actually responds to the other party is stored in the SDP header. It is described in the “s” field, which is a field that does not involve the SIP server (S108). After the processing operation of S106 or S108, the generated response message “200 OK” is transmitted to the calling device 1A (S109, T3).

  When the SIP server 20 receives the response message “200 OK” from the called device 1B, if the SIP server 20 imposes a restriction on the SDP header format, the SDP header in the response message indicates that the SIP server It is determined whether or not it conforms to the requested format, and if it conforms to the format, a response message is transferred to the calling party (T4). On the other hand, if it does not match, an error message is returned to the called side device 1B, and the response message is not transferred to the calling side.

  The called device 1B that has sent the response message in S109 receives the error message from the SIP server 20 without receiving the final response confirmation response “ACK” from the called device 1A that is the counterpart. (S110: NO), predetermined response error processing is performed (S111). For example, response error information is recorded in a log file, or a response message such as “Response error. Check if the set carrier matches the carrier to which the device is connected.” A character string for notifying the user that an error has occurred without passing through the SIP server 20 is displayed on the display unit 11, or the character string is printed out in the recording unit 10.

  On the other hand, if the calling side device 1A receives the response message “200 OK” sent by the called side device 1B in S109 through the SIP server 20 (S9: YES, T4), the calling side device 1A sends a final response confirmation response “ACK”. This is transmitted to the called device 1B (T5), and the called device 1B receives “ACK” (S110: YES). Next, a media session is established between both apparatuses 1A and 1B (S11, S112), and data communication processing such as image data is performed (S12, S112). After the data communication processing is completed, a request message “BYE” is transmitted from the calling side device 1A to the called side device 1B via the SIP server 20 (T6), and the called side device 1B sends the calling side device 1A. After the response message “200 OK” is sent back to the SIP server 20 (T7), the media session is disconnected.

  In the embodiment of the present invention, when the SIP server to which the facsimile apparatus is connected imposes a restriction on the SDP header format, the information about the media session requested or responded to the other party is not included in the SDP header. Although described in the “s” field, the description location is not limited to this as long as the SIP server is not involved, such as “v” and “t” fields, SIP headers, and the like. May be.

  In the embodiment of the communication procedure described with reference to FIG. 3, the case where one SIP server 20 is interposed between the calling side device 1A and the called side device 1B has been described. Thus, even if there are two or more SIP servers that impose restrictions on the SDP header format between the calling side device 1A and the called side device 1B, both the devices 1A, 1B are not restricted by the SIP server. In addition, it is possible to freely send and receive image data by making arrangements regarding media sessions. In other words, the calling side device 1A and the called side device 1B, in the SIP signaling message exchanged with each other, follow the SDP header format conforming to the nearest SIP server 21 and 22 to which the devices 1A and 1B are directly connected, respectively. In addition to describing the header, information about the media session that is actually requested or responded to the other party is described in a place where the respective SIP servers 21 and 22 are not involved, for example, in the “s” field of the SDP header. For this reason, even when two or more SIP servers are interposed between the both apparatuses 1A and 1B, the object of the present invention is similarly achieved, and the same operational effects can be achieved.

  The present invention can be applied to, for example, an image communication apparatus that transmits and receives image data in a media session established by SIP.

1 is a diagram illustrating a configuration example of a facsimile apparatus (image communication apparatus) according to an embodiment of the present invention. FIG. It is the figure which showed an example of the table which concerns on embodiment of this invention. It is the sequence diagram which showed the communication procedure formed between the calling side and called side facsimile apparatus (image communication apparatus) and SIP server which concern on embodiment of this invention. 6 is a flowchart showing a processing operation executed when the facsimile apparatus (image communication apparatus) according to the embodiment of the present invention performs a transmission operation. 6 is a flowchart showing processing operations executed when the facsimile apparatus (image communication apparatus) according to the embodiment of the present invention receives “INVITE” which is a request for establishing a media session. FIG. 3 is a sequence diagram showing a communication procedure formed between a calling side and called side facsimile apparatus (image communication apparatus) and a SIP server according to an embodiment of the present invention, in the case where two SIP servers intervene It is the figure which showed the example of.

Explanation of symbols

1, 1A, 1B Facsimile device (image communication device)
2 CPU
3 ROM
4 RAM
M Request message (call control protocol message)
X table

Claims (4)

  In an image communication apparatus that establishes a media session and transmits image data by exchanging a call control protocol message with a counterpart, storage means for storing an SDP header format suitable for the server of the carrier to which the apparatus is connected; A first description means for describing the SDP header of the request message to be transmitted in accordance with the SDP header format stored in the storage means, and a media session that actually requests the other party at a predetermined location not associated with the server in the request message And a second description means for describing information relating to the image communication apparatus.   2. The image communication apparatus according to claim 1, wherein the predetermined part in which the second description unit describes information related to the media session is a specific field of an SDP header described by the first description unit. An image communication apparatus for receiving image data to establish a media session by exchanging messages of a destination call control protocol, receives a request message described in accordance with SDP header format in the request message received An image communication apparatus comprising means for adopting, as information relating to a media session requested by a partner, information described in a predetermined location not involving a server that controls call control.   The image communication apparatus according to claim 3, wherein the predetermined part where the server is not involved is a specific field of an SDP header in the received request message.

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