Patent Publication Number: US-2002001373-A1

Title: Internet facsimile gateway apparatus and method for controlling the same

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to an Internet facsimile gateway apparatus and, in particular, to a gateway apparatus, which is connected to an IP network and a public network, for performing G3 facsimile mutual communication on a real time basis based on the T.38 recommended by the ITU-T.  
       BACKGROUND OF THE INVENTION  
       [0002] In recent years, as the Internet can be utilized at low price, there is an increasing tendency to attempt to reduce costs by transmitting voices and facsimiles using the Internet or to attempt to improve transmission efficiency by uniting data such as voices, facsimiles and videos using the Internet (IP network).  
       [0003]FIG. 10 shows a network configuration for transmitting a document in a G3 facsimile apparatus via an IP network. Reference numerals  1201  and  1202  denote an Internet facsimile gateway apparatuses (GWs), which are connected to an IP network  200  and public networks  2101  and  2102 , respectively. Reference numerals  2201  and  2202  denote G3 facsimile apparatuses, which are connected to the public networks  2101  and  2102 , respectively.  
       [0004] The gateway apparatuses  1201  and  1202  perform communication with the G3 facsimile apparatuses  2201  and  2202  in accordance with the T.30 (a recommendation by the ITU-T and procedures for facsimile transmission of a document in a general switching telephone network) protocol. In addition, the gateway apparatuses mutually perform UDP (User Datagram Protocol in accordance with the RFC 768  of the IETF) communication by the IFP (Internet Facsimile Protocol) packet in the UDPTL/IP (Facsimile UDP Transport Layer Protocol) in accordance with the T.38 (a recommendation by the ITU-T and procedures for the real time G3 facsimile communication on the IP network) protocol.  
       [0005]FIG. 11 shows a UDPTL/IP packet configuration defined by the T.38 protocol. A UDPTL/IP packet  300  is composed of an IP header, a UDP header, a UDPTL header and an IFP packet. In addition, the IFP packet is composed of a type and data  310 .  
       [0006]FIG. 12 is a block diagram showing a brief configuration of a conventional Internet facsimile gateway apparatus. An Internet facsimile gateway apparatus  1200  shown in FIG. 12 corresponds to the gateway apparatuses  1201  and  1202  in FIG. 10.  
       [0007] In this figure, reference numeral  104  denotes a control section, which controls the entire apparatus. Reference numeral  101  denotes a public network control section, which is connected to a public network and controls incoming and outgoing calls. Reference numeral  102  denotes a facsimile signal processing section performs generation and detection of various kinds of signals defined in the T.30, modulation of data to be transmitted to a public network signal, and demodulation of a signal received form the public network to digital data. Reference numeral  103  denotes a T.30 protocol processing section, which performs protocol processing in accordance with the T.30 protocol. Reference numeral  106  denotes a packet processing section, which assembles and disassembles the UDPTL/IP packet and takes out data in the IFP from the UDPTL/IP packet. Reference numeral  105  denotes a data buffer, which stores transmission and reception data of the IFP packet. Reference numeral  109  denotes a LAN control section, which performs control of transmission of data to a LAN or receipt of data from a LAN.  
       [0008] A part of mutual communication operations of G3 facsimile apparatuses via the IP network will be hereinafter described with reference to FIGS. 13 and 14.  
       [0009]FIG. 13 shows a signal sequence from the time when an outgoing call side G3 facsimile apparatus (the G3 facsimile apparatus  2201  in FIG. 10) makes a transmission until the time when it receives a DIS (Digital Identification Signal) from an incoming call side G3 facsimile apparatus (the G3 facsimile apparatus  2202  in FIG. 10) (however, operations of a switching machine of the public network is omitted).  
       [0010] In FIG. 13, reference numeral  400  denotes a signal state of the outgoing call side G3 facsimile apparatus  2201 , reference numeral  401  denotes a signal state of the outgoing side gateway apparatus  1201 , reference numeral  402  denotes a signal state of the incoming side gateway apparatus  1202 , and reference numeral  403  denotes a signal state of the incoming side G3 facsimile apparatus  2202 , respectively. When receiving transmission  410  from the outgoing call side G3 facsimile apparatus  2201 , the outgoing side gateway apparatus  1201  transmits transmission information  420  to the incoming side gateway apparatus  1202 . When receiving the transmission information  420 , the incoming side gateway apparatus  1202  transmits receipt  430  to the incoming call side G3 facsimile apparatus  2202 .  
       [0011] When responding to the receipt  430 , the incoming call side G3 facsimile apparatus  2202  transmits a CED (Called station identification) signal  431  in accordance with the T.30 protocol. When receiving the CED signal, the incoming side gateway apparatus  1202  transmits CED data  421  by an IFP packet frame in accordance with the T.38 protocol. When receiving the CED data  421 , the outgoing side gateway apparatus  1201  transmits a CED signal  411  to the outgoing call side G3 facsimile apparatus  1201  in accordance with the T.30 protocol.  
       [0012] After transmitting the CED signal  431 , the incoming call side G3 facsimile apparatus  2202  transmits a preamble signal  432  following a no-signal state  450  of 75±20 ms. The incoming gateway apparatus  1202  transmits preamble data  422  by an IFP packet. At this point, since an IP network  200  is provided between the incoming side gateway apparatus  1202  and the outgoing side gateway apparatus  1201 , transmission delay occurs which is generally longer than that occurring in a telephone switched network. When a delayed time of the IP network at a time t is assumed to be Td(t) ms, it takes Td(t) ms for the IFP packet of the preamble data  422  to reach the outgoing side gateway apparatus  1201 .  
       [0013] Thereafter, since the outgoing side gateway apparatus  1201  transmits a preamble signal  425  to the outgoing call side G3 facsimile apparatus  2201  in accordance with the T.30 protocol, a no-signal state  428  between the preamble signal  425  and the CED signal  411  which reach the outgoing call side G3 facsimile apparatus  2201  occurs for (75±20)+Td(t)ms.  
       [0014] The incoming call side G3 facsimile apparatus  2202  transmits a CSI (Called Subscriber Identification) signal  433  and a DIS (Digital Identification Signal)  434  following the preamble signal  425 . The incoming side gateway apparatus  1202  transmits CSI data  423  and DIS data  424  to the outgoing side gateway apparatus  1201  by an IFP packet frame. The outgoing side gateway apparatus  1201  transmits the received data to the outgoing call side G3 facsimile apparatus  2201  as a CSI signal  426  and DIS  427 .  
       [0015]FIG. 14 shows a signal sequence for switching a low speed modem to a high speed modem and training the high speed modem prior to transmission of image data from the outgoing call side G3 facsimile apparatus  2201 . The outgoing side G3 facsimile apparatus  2201  continuously transmits a preamble signal  800 , a TSI (Transmitting Subscriber Identification) signal  801  and a DCS (Digital Command Signal)  802  by a low speed modem. When receiving these signals, the outgoing side gateway apparatus  1201  continuously transmits an IFP packet of preamble data  810 , an IFP packet of TSI data  811  and an IFP packet  812  of DCS data in accordance with the T.38 protocol.  
       [0016] The incoming side gateway apparatus  1202  transmits a preamble signal  815 , a TSI signal  816  and a DCS signal  817  to the incoming call side G3 facsimile apparatus  2202  in accordance with the T.30 protocol, respectively. After transmitting the DCS signal  802 , the outgoing call side G3 facsimile apparatus  2201  causes a no-signal state  830  of 75±20 ms to occur, and then transmits a training signal  803  for training the high speed modem. When receiving the training signal  803 , the outgoing side gateway apparatus  1201  transmits an IFP packet of training signal  813  to the incoming side gateway apparatus  1202  in accordance with the T.38 protocol.  
       [0017] At this point, as described in FIG. 13 as well, delay of Td(t) ms occurs in data transmission by the IP network between the outgoing side gateway apparatus  1201  and the incoming side gateway apparatus  1202 . Therefore, it takes Td(t) ms since the transmission by the outgoing side gateway apparatus  1201  for the IFP packet to reach the incoming side gateway apparatus  1202 . When receiving the IFP packet, since the incoming side gateway apparatus  1202  transmits a training signal  818  in accordance with the T.30 protocol, a no-signal state  820  between the DCS  817  and the training signal  818  which reach the incoming call side G3 facsimile apparatus  2202  occurs for (75±20)+Td(t)ms.  
       [0018] The outgoing call side G3 facsimile apparatus  2201  transmits a TCF (Training Check) signal  804  following the training signal  803 , the outgoing side gateway apparatus  1201  transmits an IFP packet  814  of TCF data to the incoming side gateway apparatus  1202  in the same manner as it transmits other signals, and the incoming side gateway apparatus  1202  transmits a TCF signal  819  to the incoming call side G3 facsimile apparatus  2202 .  
       [0019] As described above, in the conventional gateway apparatus, a no-signal interval that is a no-signal interval generated by the G3 facsimile apparatus in accordance with the T.30 protocol to which transmission delay via the IP network is added occurs in a counterpart&#39;s facsimile apparatus. Thus, depending on a length of a no-signal interval generated by the G3 facsimile apparatus and an amount of transmission delay of the IP network, a length of a no-signal interval of a defined value of the T.30 protocol, for example, 75±20 ms could not be satisfied. Therefore, due to this extended no-signal state, a phenomenon occurred in which an echo suppressor or an echo canceller of a public network operated and a full duplex communication between G3 facsimile apparatuses was not normally performed.  
       SUMMARY OF THE INVENTION  
       [0020] The present invention has been devised in view of these problems of the conventional art, and it is an object of the present invention to provide an Internet facsimile gateway apparatus and a method for controlling the same which can certainly perform mutual communication between facsimile apparatuses without depending on transmission delay of an IP network that connects between gateway apparatuses.  
       [0021] That is, an aspect of the present invention is an Internet facsimile gateway apparatus that is connected to a general switched telephone network and an IP network and relays facsimile communication between the general switched telephone network and the IP network, which comprises: first communicating means for performing procedural processing of facsimile transmission in the general switched telephone network; second communicating means for performing procedural processing of facsimile transmission in the IP network; and controlling means for controlling a transmission timing of a signal transmitted from the first communicating means based on a signal received by the second communicating means.  
       [0022] In addition, another aspect of the present invention is a method for controlling an Internet facsimile gateway apparatus that is connected to a general switched telephone network and an IP network and relays facsimile communication between the general switched telephone network and the IP network, which comprises: a first communication step of performing procedural processing of facsimile transmission in the general switched telephone network; a second communication step of performing procedural processing of facsimile transmission in the IP network; and a control step for controlling a transmission timing of a signal transmitted by the first communication step based on a signal received by the second communication step.  
       [0023] In addition, another aspect of the present invention is a computer readable recording medium that stores a control program of an Internet facsimile gateway apparatus that is connected to a general switched telephone network and an IP network and relays facsimile communication between the general switched telephone network and the IP network, which comprises: a program of a first communication step for performing procedural processing of facsimile transmission in the general switched telephone network; a program of a second communication step for performing procedural processing of facsimile transmission in the IP network; and a program of a control step for controlling a transmission timing of a signal transmitted by the program of the first communication step based on a signal received by the program of the second communication step. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0024] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.  
     [0025]FIG. 1 is a block diagram showing an example of a configuration of an Internet facsimile gateway apparatus in accordance with an embodiment of the present invention;  
     [0026]FIG. 2 is a schematic illustration showing a network configuration of the embodiment of the present invention;  
     [0027]FIG. 3 is a schematic illustration showing an outgoing side signal sequence in accordance with a first embodiment of the present invention;  
     [0028]FIG. 4 is a flow chart showing operations of an Internet facsimile gateway apparatus in accordance with the first embodiment of the present invention;  
     [0029]FIG. 5 is a schematic illustration showing an outgoing side signal sequence in accordance with a second embodiment of the present invention;  
     [0030]FIG. 6 is a flow chart showing operations of an Internet facsimile gateway apparatus in accordance with the second embodiment of the present invention;  
     [0031]FIG. 7 is a schematic illustration showing an incoming side signal sequence in accordance a third embodiment of the present invention;  
     [0032]FIG. 8 is a flow chart showing operations of an Internet facsimile gateway apparatus in accordance with the third embodiment of the present invention;  
     [0033]FIG. 9 is a schematic illustration sowing an example of stored contents of a sequence storage section in accordance with the embodiment of the present invention;  
     [0034]FIG. 10 is a schematic illustration showing a conventional network configuration;  
     [0035]FIG. 11 is a schematic illustration showing a configuration of a UDPTL/IP packet;  
     [0036]FIG. 12 is a block diagram showing an example of a configuration of a conventional Internet facsimile gateway apparatus;  
     [0037]FIG. 13 is a schematic illustration showing a conventional outgoing side signal sequence; and  
     [0038]FIG. 14 is a schematic illustration showing a conventional incoming side signal sequence. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0039] Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings.  
     [0040] [First Embodiment]  
     [0041]FIG. 1 is a block diagram showing an example of a configuration of an Internet facsimile gateway apparatus in accordance with a first embodiment of the present invention.  
     [0042] In FIG. 1, same reference numerals are given to elements  101  to  106  and  109  that are the same as those in a conventional Internet facsimile gateway apparatus  1200  shown in FIG. 12, and repeated descriptions are omitted.  
     [0043] Reference numeral  107  denotes a data analysis section, which analyzes data stored in a data buffer  105 . Reference numeral  108  denotes a local preamble data generation section, which stores preamble signals determined in advance. Reference numeral  110  denotes a no-signal state generation section, which generates a no-signal state to a public network. Reference numeral  111  denotes a switching control section with a timer, which switches a state of a no-signal state generation section  110  for a predetermined length of time in accordance with an instruction of a control section  104 . Reference numeral  112  denotes a sequence storage section, which stores a signal of the T.30 , information received from the IP network  1200 , and operations to the public network which should be performed according to the received information, and is referenced by a data analysis section  107 .  
     [0044]FIG. 2 shows a network configuration for transmitting a document of the G3 facsimile apparatus via the IP network, which has the Internet facsimile gateway apparatuses  1001  and  1002  having the configuration shown in FIG. 1 instead of Internet facsimile gateway apparatuses  1201  and  1202  in FIG. 10.  
     [0045] Operations of the Internet facsimile gateway apparatus in this embodiment will be hereinafter described. FIG. 3 shows a part of mutual communication operations of the G3 facsimile apparatus via the IP network as FIG. 13 does. In addition, in the following description, sequence operations since an outgoing call side G3 facsimile apparatus  2201  makes a transmission until it receives a DIS from an incoming call side G3 facsimile apparatus  2202  are described.  
     [0046]FIG. 3 shows an outgoing side signal sequence, and FIG. 4 shows an operation flow chart of the Internet facsimile gateway apparatus  1001  in the outgoing side. However, operations of a switch board of a public network are omitted. In FIG. 3, reference numeral  400  denotes a signal state of the outgoing call side G3 facsimile apparatus  2201 , reference numeral  404  denotes a signal state of the outgoing side gateway apparatus  1001 , reference numeral  405  denotes a signal state of the incoming side gateway apparatus  1002 , and reference numeral  403  denotes a signal state of the incoming call side G3 facsimile apparatus  2202 , respectively. In addition, same reference numerals are given to signals that are the same as those in FIG. 13.  
     [0047] Here, transmission  410  indicates that operations for connecting to the outgoing side gateway apparatus (GW)  1001  is performed and the outgoing call side G3 facsimile apparatus  2201  is in the transmission state via the a public network  2101 . In addition, the incoming side gateway apparatus (GW)  1002  indicates that a receipt signal  430  is notified to the G3 facsimile apparatus  2202  via a public network  2102 , and indicates that the G3 facsimile apparatus  2202  is in the receipt state. Moreover, it goes without saying that various signals in accordance with the T.30 protocol are transmitted and received via the public networks  2101  and  2102 .  
     [0048] In addition, in the following description, elements of the Internet facsimile gateway apparatuses  1001  and those of the Internet facsimile gateway apparatuses  1002  are distinguished by attaching “1” and “2” at the last of the reference numerals, respectively. For example, a public network control section of the Internet facsimile gateway apparatus  1001  is represented as  1011 , and a public network control section of the Internet facsimile gateway apparatus  1002  is represented as  1012 .  
     [0049] First, when it is assumed that the outgoing call side G3 facsimile apparatus  2201  receives the transmission  410 , the outgoing side GW  1001  detects a transmission state by a control section  1041  via the public network control section  1011 . Then, information of the outgoing call side G3 facsimile apparatus  2201 , transmission information  420  such as a telephone number of a counterpart, or the like is transmitted to the incoming side GW  1002  by a TCP/IP packet via a packet processing section  1061 , an LAN control section  1091 , an LAN and an IP network  200 .  
     [0050] When the incoming side GW  1002  receives and detects the transmission information  420  via an LAN control section  1092  and a packet processing section  1062 , the public network control section  1012  moves to incoming connection operations to the incoming call side G3 facsimile apparatuses  2202 . When detecting a predetermined receipt  430 , the incoming call side G3 facsimile apparatus  2202  transmits the CED signal  431  immediately to the receipt GW  1002 .  
     [0051] When the incoming side GW  1002  receives the CED signal  431  in the public network control section  1012  and the CED signal is detected in the facsimile signal processing section  1022 , the detection data is communicated to a control section  1042  via a T.30 protocol processing section  1032 . The control section  1042  instructs a packet processing section  1062  to communicate the CED data (a data value indicating the CED) to the outgoing side GW  1001  by a UDPTL/IP packet. The packet processing section  1062  puts the CED data in a data section  310  of the IFP packet, and transmits it to the IP network  200  via the LAN control section  1092 .  
     [0052] When received by the LAN control section  1091  of the outgoing side GW  1001 , a UDPTL/IP packet  421  including the CED data is disassembled into IFP packets in the packet processing section  1061 , and the CED data of the data section  310  is stored a the data buffer  1051  one after another. The control section  1041  reads the stored data from the data buffer  1051  one after another, and transfers the data to a data analysis section  1071 .  
     [0053] The data analysis section  1071  performs analysis of data, and determines whether or not the data coincides with defined sequence signal information by accessing a sequence storage section  1121 . When the control section  1041  recognizes that CED data and the received data because the CED data is stored in the sequence storage section  1121 , the control section  1041  performs operations in accordance with an operational sequence stored in the sequence storage section  1121  as well. That is, as shown in FIG. 9, when the end of the CED signal is detected, the control section  1041  operates such that a no-signal state of 75±20 ms is generated with respect to the public network. This operation will be hereinafter described in detail using the flow chart shown in FIG. 4.  
     [0054] When confirming the receipt of the CED, the control section  1041  issues a CED transmission instruction to a T.30 protocol processing section  1031 . The T.30 protocol processing section  1031  forwards CED data to a facsimile processing section  1021  instructing the facsimile processing section  1021  to transmit the CED signal  411 . Then, the CED signal  411  is transmitted to the outgoing call side G3 facsimile apparatus  2201 . When the data analysis section  1071  detects the end of the CED (step S 500 ), the transmission of the CED signal  411  is stopped, and the control section  1041  instructs a switching control section with timer  1111  to switch a no-signal state generation section  1101  to a no-signal state.  
     [0055] Thereafter, the no-signal state generation section  1101  is activated, and a no-signal state  440  of 75±20 ms is generated to the public network  2101  (step S 502 ). After the no-signal state of 75±20 ms, the switching control section  1111  switches the no-signal state generation section  1101  from the no-signal state to the facsimile signal processing section  1021  side. Then, the control section  1041  reads the preamble data from a local preamble data generation section  1081 , demodulates the data in the facsimile signal processing section  1021  via the T.30 protocol processing section  1031 , and transmits the demodulated data to the outgoing call side G3 facsimile apparatus  2201  as a preamble signal  412  (step S 503 ).  
     [0056] In this way, it is seen that the no-signal state of 75±20 ms can be certainly secured by the outgoing side GW  1001  transmitting a preamble signal locally. After finishing transmitting the CED signal  431  for a predetermined length of time, the incoming call side G3 facsimile apparatus  2202  transmits a preamble signal  432  through a no-signal state  450  of 75±20 ms.  
     [0057] A UDPTL/IP packet  432  in which the preamble data  422  was put in the data section of the IFP packet is transmitted to the outgoing side GW  1001  via the incoming side GW  1002  and the IP network  200 . when the outgoing side GW  1001  receives this packet  432 , the preamble data is detected in the data analysis section  1071  via the LAN control section  1091 , the packet processing section  1061  and the data buffer  1051  (step S 504 ).  
     [0058] When the preamble signal from the incoming call side G3 facsimile apparatus  2202  is detected, the outgoing side GW  1001  stops the transmission of the local preamble data signal  412 , and continues to transmit a preamble signal based on preamble data read from the data buffer  1051 . In this case, the local preamble signal can be transmitted without change.  
     [0059] After transmitting the preamble signal  432  for a predetermined length of time, the incoming call side G3 facsimile apparatus  2202  continuously transmits a CSI (Called Station Identification) signal  433  and a DIS (Digital Identification Signal)  434 . CSI data  423  and DIS data  424  are put in the data section of the IFP packet in the incoming side GW  1002 , respectively, and transmitted to the outgoing side GW  1001  by the UDPTL/IP packets  423  and  424 .  
     [0060] Although the outgoing side GW  1001  performs processing in a route similar to that of the preamble data  422 , if the CSI packet  423  and the DIS packet  424  do not reach the outgoing side GW  1001  continuously (substantially simultaneously), the outgoing side GW  1001  transmits a CSI signal  413  and a DIS signal  414  one after another to the outgoing call side G3 facsimile apparatus  2201  after DIS data  424  reaches the outgoing side GW  1001 .  
     [0061] That is, even after detecting the CSI (step S 506 ), the outgoing side GW  1001  continues to transmit a preamble signal while retaining the CSI data (step S 507 ). Thereafter, when detecting the DIS data (step S 508 ), the outgoing side GW  1001  stops the transmission of the preamble signal (step S 509 ), transmits the CSI signal  413  (step S 510 ), and successively transmits the DIS signal  414  (step S 511 ). In this way, the CSI signal and the DIS signal can be transmitted to the G3 facsimile apparatus within a predetermined length of time with retaining synchronism as established.  
     [0062] [second Embodiment] In the first embodiment, if the UDPTL/IP packet including the CSI data from the incoming side GW  1002  and the packet including the DIS data do not reach continuously (substantially simultaneously), the transmission of the preamble signal is continued until the receipt of the DIS data is detected. The second embodiment is characterized by transmitting the CSI signal first in such a case.  
     [0063] Operations of the outgoing side GW  1101  in this embodiment will be hereinafter described using a sequence chart shown in FIG. 5 and a flow chart shown in FIG. 6. Further, in the sequence chart of FIG. 5 and the flow chart of FIG. 6, identical reference numerals are given to the signals and processing with the contents identical with those of the sequence chart of FIG. 3 and the flow chart of FIG. 4, and repeated descriptions are omitted.  
     [0064] Therefore, only processing after the step S 506  and a sequence after receiving the CSI packet  423  will be hereinafter described. When detecting the receipt of the CSI packet  423  (step S 506 ), the outgoing side GW  1101  once stops the transmission of the preamble signal (step S 700 ). Then, the outgoing side GW  1101  generates the CSI signal  413  from the CSI packet  423  that has reached earlier, and transmits it to the outgoing call side G3 facsimile apparatus  2201  (step S 701 ).  
     [0065] Then, the outgoing side GW  1001  starts timing of a predetermined length of time in order to measure time-out of the DSI data detection (step S 706 ). If the DSI data is detected in the predetermined length of time (step S 702  to S 704 ), the outgoing side GW  1001  transmits the data to the G3 facsimile apparatus  2201  by switching to the DIS signal  414  (step S 707  to S 705 ). If the DSI data is not detected when the predetermined length of time has passed, the outgoing side GW  1001  determines time-out in step S 702 , starts the transmission of the preamble signal  415  (step S 703 ), and starts the timing processing again while retaining synchronism. Thereafter, if the DSI data is detected (step S 704 ), the outgoing side GW  1001  stops the transmission of the preamble signal (step S 708 ) and then transmits DIS signal  414  (step S 705 ). In this way, communication is continuously established without breaking the synchronism of the outgoing call side G3 facsimile apparatus  2201  and the outgoing side GW  1001 .  
     [0066] [Third embodiment] Operations for switching to a high speed modem and training the high speed modem prior to transmitting image data from the outgoing call side G3 facsimile apparatus  2201  will now be described with reference to FIGS. 7 and 8. FIG. 7 shows a signal sequence and FIG. 8 shows an operation flow chart of the incoming side Internet facsimile gateway apparatus  1002  of this embodiment. Further, in FIG. 7, same reference numerals are given to signals that are the same as those in the conventional incoming side signal sequence shown in FIG. 14.  
     [0067] As described in the first and the second embodiments, when transmitting various signals to the outgoing side GW  1101  after receipt, and transmitting the UDPTL/IP packet having the DIS data (step S 900 ), the incoming side GW  1002  is in the state of waiting for data from the outgoing side GW  1101 .  
     [0068] The outgoing call side G3 facsimile apparatus  2201  continuously transmits a preamble signal  800 , a TSI (Transmitting Station Identification) signal  801  and a DCS (Digital Command Signal)  802  by a low speed modem. When the outgoing side GW  1001  receives these signals, the signals are transferred to the control section  1041  via the public network control section  1011 , the facsimile processing section  1021  and the T.30 protocol processing section  1031 .  
     [0069] The preamble data, the TSI data and DCS data are put in the data section of the IFP packet, respectively, in accordance with the T.38 protocol in the packet processing section  1061 , and are transmitted to the IP network  200  by the UDPTL/IP packet  810 ,  811  and  812 . The incoming side GW  1002  receives these packets in the LAN control section  1092 , disassembles them into data of the IFP packet in the packet processing section  1062 , and stores each piece of the data in the data buffer  1052  one after another (step S 901  to S 903 ). The control section  1042  transfers these pieces of the data to the data analysis section  1072  one after another.  
     [0070] The data analysis section  1072  notifies the control section  1042  of analysis results. At this point, the data analysis section  1072  accesses a sequence storage section  1122 . As shown in FIG. 9, information received from the IP network  200  and operations with respect to the public network that should be performed according to the information are stored in the sequence storage section. Therefore, since the data analysis section  1072  can recognize in advance a sequence to be switched to a training signal because a non-signal state of 75±20 ms follows the DCS by accessing the sequence storage section  1122 , the data analysis section  1072  operates to retain the data without transmitting each signal to the incoming call side G3 facsimile apparatus  2202  immediately in accordance with the contents of operations in FIG. 9.  
     [0071] The outgoing call side G3 facsimile apparatus  2201  generates a no-signal state  830  of 75±20 ms after the transmission of the DCS signal  802  and, then, transmits the training signal  803  of the high speed modem. When receiving the training signal  803 , the outgoing side GW  1001  puts training data in the data section of the IFP packet and transmits the data to the incoming side GW  1002  by the UDPTL/IP packet  813  according to the similar processing routes as described above.  
     [0072] In addition, the outgoing call side G3 facsimile apparatus  2201  transmits a TCF (Training Check) signal after transmitting the training signal  803  for a predetermined length of time. The TCF data is also transmitted to the incoming side GW  1002  by the UDPTL/IP packet  814 . When the incoming side GW  1002  receives the training data (step S 904 ) and receives the TCF data (step S 905 ), the control section  1042  reads the pieces of data from the data buffer  1052  one after another, and transmits the data to the facsimile signal processing section  1022  via the T.30 protocol processing section  1032 .  
     [0073] The facsimile signal processing section  1022  demodulates these pieces of data to a facsimile communication signal, transmits a preamble signal  820  (step S 906 ), transmits a TSI signal  821  (step S 907 ) and transmits a DCS signal  822  (step S 908 ) to the incoming call side G3 facsimile apparatus  2202 , and, then, the control section  1042  instructs a switching control section  1112  with timer to switch to a no-signal state of 75±20 ms (step S 909 ) and creates a no-signal state  840 .  
     [0074] Thereafter, when the no-signal state is finished by the switching control section  1112  with timer, the facsimile signal processing section  1022  transmits a training signal  823  (step S 910 ) and then transmits a TCF signal  824 . In this way, a length of time of the no-signal state from the receipt of the DCS signal to the receipt of the training signal of 75±20 ms can be accurately secured in the incoming call side G3 facsimile apparatus  2202 .  
     [0075] Although a gateway apparatus for communication between G3 facsimile apparatuses is described in the above-mentioned embodiment, the present invention may be a gateway apparatus of an apparatus for performing facsimile communication by other standards because the essence of the present invention is in generating a pseudo signal in gateway apparatuses when normal communication is difficult between facsimile apparatuses due to transfer delay by an IP network between the gateway apparatuses or realizing normal communication by controlling a transmission timing of a signal.  
     [0076] In addition, it goes without saying that a facsimile apparatus needs not to be a machine only for a facsimile, but an apparatus having a function of facsimile communication will suffice. That is, a facsimile apparatus may be a copying machine having a facsimile communication function, a computer apparatus having a facsimile modem or the like.  
     [0077] Further, the present invention may be applied to a system composed of a plurality of apparatuses (e.g., a host computer, interface equipment, a reader and a printer) or may be applied to an apparatus consisting of one appliance (e.g., a copying machine and a facsimile apparatus).  
     [0078] In addition, it goes without saying that the object of the present invention can be attained by supplying a storage medium (or a recording medium) that records a program code of software for realizing the functions of the above-mentioned embodiments to a system or an apparatus, and by a computer (CPU or MPU) of the system or the apparatus reading and executing the program code stored in the storage medium. In this case, since the program code itself read from the storage medium realizes the functions of the above-mentioned embodiments, and the storage medium storing the program code constitutes the present invention. In addition, the object of the present invention can also be attained not only in the case in which the functions of the above-mentioned embodiments are realized by executing a program code read by a computer but also in the case in which an operating system (OS) or the like that runs on the computer performs a part or all of actual processing based on the instruction of the program code, thereby realizing the functions of the above-mentioned embodiments.  
     [0079] Moreover, the object of the present invention can also be attained in the case in which, after a program code read from the storage medium is written in a memory provided in a function extension card inserted in a computer or a function extension unit connected to a computer, a CPU or the like provided in the function extension card or the function extension unit performs a part or all of actual processing, thereby realizing the functions of the above-mentioned embodiments.  
     [0080] If the present invention is applied to the above-mentioned storage medium, a program code corresponding to a flow chart described before (shown in any one of FIGS. 4, 6 and  8 )is stored in the storage medium.  
     [0081] As described above in detail, according to the present invention, since a necessary signal is transmitted and a no-signal state can be created even in the case in which time delay occurs in an IP network, mutual communication with a G3 facsimile apparatus can be secured, and full duplex communication can be performed without operating an echo suppressor or an echo canceller of a public network. Therefore, a high quality apparatus with high reliability can be provided which is capable of performing real time Internet facsimile communication between G3 facsimile apparatuses via an IP network and is not affected by time delay of the IP network.  
     [0082] Furthermore, the present invention can be applied to the system comprising either a plurality of units or a single unit. It is needless to say that the present invention can be applied to the case which can be attained by supplying programs which execute the process defined by the present system or invention.