FR2754124A1 - TELEPHONY GATEWAY ON THE INTERNET - Google Patents

Abstract

This device is characterized in that it comprises: - a first interface unit for connection to the switched network; - a second interface unit for connection to the packet switching network; - means for receiving signals at said first interface and for converting them into data packets for their transmission over the packet switching network and vice versa and; a processing means for determining the destination information from the signals or data packets originating from the aforementioned first network, and establishing communication to the destination address on the aforesaid second network as a function of said destination information.

Description

TELEPHONY GATEWAY ON THE INTERNET

  Apparatus for establishing telephone communications between a packet switching network carrying data packets, and a switched network carrying telephone signals, comprising a first interface unit for connection to the switched network, a second interface unit for connection to the packet switching network, a device for receiving signals at said first interface and for converting them into data packets for transmission on the packet switching network and vice versa, and a processor for determine the destination information from signals or data packets from one network, and establish communication to the destination address on the other network based on

the destination information.

  The present invention relates to an Internet Telephony Gateway, and more particularly to a gateway for establishing a telephone call from a telephone set.

  ordinary to an Internet subscriber.

  For many years, the Public Switch Telephone Network (PSTN) has allowed subscribers to establish dial-up telephone communications. The circuits are established at the time of the call and remain dedicated to subscribers online

  throughout the duration of the communication.

  More recently, the Internet has become a widely used means of communication. The Internet is constituted by the interconnection of a multitude of networks, all using the TCP / IP protocol (Transmission Control Protocol / Internet Protocol), so that users these networks can communicate. Unlike the PSTN network, the Internet is a packet switching network, that is, a network on which data is routed as packets addressed individually from the sender to the receiver. The Internet is suitable for non-critical data, for example for file transfer or e-mail, although it has recently been widely used for real-time applications. It has been possible for a long time to communicate in real time on the Internet through "discussion forums". In these, users communicate by entering real-time data from the keyboard of their computer. A recently released software allows, in conjunction with an audio card, to exchange voice in real time on the Internet. Subscribers have the opportunity to have "telephone conversations"

in real time via the Internet.

  The disadvantage of this software however is that it only allows communication between Internet subscribers. The receiving subscriber must have a computer connected to the Internet and appropriate software in the receive mode. An Internet subscriber can not communicate with an Ordinary Telephone Service (POTS) subscriber

  standard phone) on the PSTN.

  One of the objects of the invention is to remedy

to this disadvantage.

  In accordance with the present invention there is provided an apparatus for establishing telephone communications between a packet switching network carrying data packets and a switched network carrying telephone signals comprising a first interface unit for connection. to the switched network, a second interface unit for connection to the packet switching network, means for receiving signals at said interface and for converting them into data packets for transmission over the packet switching network and vice versa. and processing means for determining the destination information from incoming signals or data packets from one network, and establishing communication at the destination address on the other network by

  according to said destination information.

  The invention thus provides a gateway through which, for example, Internet users can call subscribers of the public switched telephone network, and vice versa. In the case of a telephone subscriber wishing to call someone on the Internet, the subscriber dials the number of the gateway which then establishes a virtual connection, via the Internet, with the user. In one embodiment, each incoming circuit on the gateway is assigned a user TCP / IP address. Alternatively, the gateway may determine the information relating to the called party from the incoming signals on a trunk link. In the opposite direction, the computer user sends a message to the gateway requesting the establishment of a call with a subscriber on the telephone of the PSTN. The gateway establishes the communication and the two correspondents can

then communicate.

  According to a second aspect of the invention, there is provided a method for establishing telephone communications between a packet switching network carrying data packets, and a switched network carrying telephone signals, comprising the steps of placing a gateway between the packet switching network and the switched network, receiving data packets from the packet switching network, sending to the gateway a call composition packet to identify the corresponding party called on the switched network, retrieving the called party number from said call dialing packet received by said gateway, setting by said gateway a call to the called number on the switched network, and the conversion to real time signals from said switched network into data packets for transmission on said switching network of pa quets and vice versa, as and when

  measuring the progress of the communication.

  The invention will now be described in more detail, without limitation, with reference to the accompanying drawings in which: FIG. 1 is a block diagram of a system using a gateway according to the invention; FIG. 2 is a block diagram showing the establishment of a communication from a computer user to a subscriber on the telephone; FIG. 3 is a block diagram showing the establishment of a call from a telephone subscriber to a computer user; FIG. 4 is a block diagram showing the routing of the voice; FIG. 5 is a block diagram of a gateway according to the invention; FIG. 6 is a more detailed block diagram of a TCP / IP module; FIG. 7 is a block diagram of a telephone interface; FIG. 8 is a top-level system flowchart; FIG. 9 is a flowchart showing the processing of an incoming call; and FIG. 10 is a flowchart showing the

  processing an outgoing call to the PSTN.

  The system shown in FIG. 1 comprises a computer access point 1 connected via Internet 2 to a telephony gateway 3. The gateway 3 - 6 - is connected via the public switched telephone network (PSTN) 4 to an individual subscriber to the telephone 5. The computer user at access point 1 and telephone subscriber at telephone station 5 can establish two-way voice communication

  in a manner to be specified below.

  Fig. 2 shows the launch of a communication from a computer user 10 to a subscriber on the telephone 11. First, the computer access point 1 formats and sends to the IIT 3 a UDP message (User Datagram Protocol = User Data Protocol), in 11. This UDP message contains information relating to the called party number on the PSTN. The ITG 3 decodes this message, picks up at 12 and calls the user 11 by dialing numbers on the PSTN as shown in block 13. In block 14, the PSTN rings the telephone set 5 and if not busy, user 11 answers. From this moment a dialogue can be established via the IIT, as indicated by block 15. Of course, if the telephone set 5 is busy, a return message signaling the occupation is sent back to the user 10 by the user. PSTN 4 via the ITG 3. From this point, the system, on the Internet side, functions in the same way as a conventional Internet telephone, and on the PSTN side, the operation is the same as that of a normal telephone set of the telephone. PSTN. On the Internet side, the computer digitizes the voice and sends it in packets to the IIT 3, where the data of the packets are disassembled and sent by the PSTN to the user of the telephone set 11, in the form of signals, either analog, either digital, for example in MIC (Pulse Code Modulation = Pulse Code

Modulation (PCM)).

  The establishment of a call by the subscriber on the telephone to a computer user is shown in FIG. 3. As shown in block 20, the telephone dials the number of the ITG 3, and the call is routed through the PSTN 4. Depending on the incoming line or called party information contained in the Incoming signals, the ITG 3, as indicated in block 21, sends a packet UDP dialing message, which is received at the computer access point 1, block 22, and in accordance with the access point software. computer, "calls" the computer if the user (is free (block 23) If the computer user is not available, a message is returned by the system and read by the PSTN. block 23, this one returns

  a busy tone to the user (block 24).

  If the computer user answers the call (block 25), the computer access point 1 sends a UDP response message to the ITG 3 which, in turn, sends the PSTN an off-hook signal which is received by PSTN 4 (block 26). The bidirectional connection

  is then established, as shown in block 27.

  Fig. 4 is a representation of the system once the dialogue has been established. Block 31 indicates the voice input of the computer user which is scanned at the computer access point, block 32, and sent as UDP packets to the ITG 3 which converts the packets to a computer. analog voice streams (but they can also remain digital) and transmits it to the PSTN 4 which routes them in 33 to the user of the telephone. In the opposite direction, user input

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  34 is transmitted via the PSTN to the ITG 3 which puts the voice input into packets and sends them as UDP packets of voice data (block 35) to the computer access point which sends it as voice output 36 Referring now to FIG. 5, the Internet Telephony Gateway (ITG) comprises a central processor system 40, for example a personal computer, connected to a system bus 41. The system bus is also connected to a switching matrix 42 and 43. The switching matrix interconnects the telephone line interface modules 44 and TCP / IP with the phase modules 45. The switching matrix 42 is connected to the module 46 of PCM (Coded Pulse Modulation) links. The messaging system 43 is connected to the interface modules via links of

message 47.

  The central processor 40 provides the higher level control of the ITG. It sends its instructions on the system bus to the messaging system 43, which in turn sends a control message to the interface modules 44 and 45 to manage the operation of these modules to establish and cut communications. The interface modules 44 and 45 function as slaves of the main processor 40. Communication state changes (e.g., creations or disconnections) are signaled to the main processor 40 via the communication links.

message 47.

  -9- Calls from the Internet are sent to the TCP / IP interface module. Incoming data packets are disassembled and routed via the switch matrix to the appropriate telephone line output module 44, from where they are sent to the PSTN as either analog or digital signals. The functioning of the system in sense

reverse is similar.

  The TCP / IP module is shown in more detail in FIG. 6. It consists of a high-speed physical interface 50, for example a T1, ISDN (Integrated Services Digital Network), PRI / BRI, etc. interface, for the TCP / IP network, which should normally be the Internet network. This interface is connected to a TCP / IP converter in a PCM 51, the entire unit being controlled by a microprocessor 52. The microprocessor has a local RAM and uses software that supports TCP / IP and connection protocols to the PC. network. As shown in FIG. 7, the telephone interface unit comprises a telephone line interface 60 and a line termination logic unit 61, which is a standard interface unit detecting the ringing tone and

other signals.

  The operation of the system will be more explicit if one refers to the flowcharts shown in Figs. 8 to 10. Referring to FIG. 8, after startup 70, the system initializes and downloads software and data tables in all modules 71. The system

  then scrutinizes any request for communication, in 72.

  Block 73 detects a ringing tone on

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  the telephone line interface, and if a ring is detected, the command is passed to block 74 which will be described in more detail with reference to FIG. 9. If no call is detected on the line interface, the system monitors, at 75, any call dialing requests from the TCP / IP interface, and if a call is detected, the command is passed. at block 76 (which will be described in more detail with respect to Fig. 10). In the absence of any call request, the system returns to block 72, and the cycle repeats. Block 74 is shown in more detail in FIG. 9. After starting 80, the main processor 40 uses the circuit identification of the transmitter's telephone line to determine the TCP / IP address of the call recipient, and transmits the dialing information. TCP / IP interface, as indicated by block 81. The TCP / IP interface module formats a UDP message (User Datagram Protocol) and sends it to the recipient computer 82. The establishment of a communication via the Internet according to this method is known

in itself.

  The ITG then waits for a UDP response message from the computer access point 83. The decision block 84 then determines whether a response has been received or not. If it is no, the command is passed to the unit 85 which determines whether the ringing tone should be stopped or not (depending on the elapsed time). If it is no, the system loops back to block 83. If yes, call dialing mode ends as indicated by block 85. If an answer is received, the

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  Decision block 84 passes to the central processor, as indicated by block 86, which then establishes a switched link through switching matrix 42 (as indicated by block 86) and the TCP / IP module starts the conversion of TCP / IP packets in PCM, as shown in block 87. At block 88, the telephone line interface module sends a pick-up signal to the subscriber's telephone set, and the two-way connection is established. The system then enters interrupt standby mode as shown in block 89. The system loops back to 90 to determine whether or not a UDP disconnect message has been received from the computer user. If yes, the system stops the procedure, as indicated

block 85.

  Fig. 10 shows in detail block 76 which processes a call dialing request from the TCP / IP interface. The system starts at 91 and uses the calling party's address contained in the call dialing UDP message, to determine the telephone interface on which the off-hook is requested, at 92. The called party's number is obtained from the dial-up packet, in 93, and the main processor establishes a PCM dial-up link between the TCP / IP module and the circuit of the selected telephone interface, block 94. The main processor connects a tone transmitter to the switched circuit , in 95. The telephone interface circuit then goes off-hook, at 96, and the dialogue is

  established when the called party answers, in 97.

  The system then waits for the interrupt procedure, at 98. When a UDP disconnect message is received,

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  decision block 99 stops communication at 100. In the embodiment described, the correspondence between each telephone line interface circuit and the TCP / IP address of a computer user is one-to-one. In other words, a phone line is assigned by the ITG to each computer. The computer user can thus indicate his ITG telephone number, and any correspondent calling this number will be connected to the computer user associated with this number. In the opposite direction, however, the computer user will be connected to the associated telephone line, but the ITG will dial the number requested by

the computer user.

  In an alternative embodiment, the ITG may be connected to a trunk link, in which case the information received on the trunk link relating to the called party may be used to determine the TCP / IP address of

  the recipient computer user.

The description above was from

  the assumption that the computer had a software subsystem implementing a form of telephony functionality on the Internet. This type of program, already widespread, translates the actions of the computer into UDP messages. The User Data Protocol (UDP) is a convenient method of exchanging messages, but it is also possible to use a similar transmission technique with reduced overhead (as

  the Express Transfer Protocol (XTP)).

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  In the above configuration, if the system is in the situation where the computer user wishes to stop the conversation, the computer access point sends the ITG 3 a UDP disconnect message. If the telephone user stops the conversation, the telephone network cuts the communication and the computer user hears only the dial tone from the network. The computer user can then disconnect himself from the network or initialize

another call.

  f The system actually allows the use of the Internet as a means for a computer user to establish two-way communication with a dedicated remote telephone line interface. For example, it is conceivable that a computer user in Ottawa / Canada who needs to make a large number of calls in the Los Angeles area can subscribe to an ITG service in the Los Angeles area. . The Ottawa computer user will have access via the Internet to a local Los Angeles line. The computer user can dial numbers from his Ottawa line as if he were physically present at a station

Los Angeles telephone.

  It was mentioned that it was possible to have a digital long distance link interface instead of the line interface described above. This solution has the advantage of no longer requiring the conversion of digital voice data into analog voice data, as well as

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  it's no longer necessary to dedicate an interface

  of line to each computer user.

  In addition, the call dialing procedures are different and imply that the ITT emits ringing and busy tones for calls to the user.

  computer, depending on the state of the user.

  On a trunk link interface, the IIT must also be ready to receive dial digits and must be able to send the calling party's registration number to the public network. For a call from a telephone subscriber to a computer, the ITG should proceed as follows (in the case of a trunk link interface). The ITG receives, via the long distance link, the number of the called party and must transcribe it to the TCP / IP address associated with the computer user. He must then try to establish a voice communication with the computer user and return on the long-distance link ringback tone or occupation depending on whether the computer user is free or already in communication elsewhere. The disconnection procedures are essentially the same as those described above. The computer user signals disconnection to the ITG by means of a UDP message, and

  The ITT sends a disconnect instruction to the PSTN.

  In the case of a call from a computer user to a subscriber on the telephone, the computer user sends the IPU a UDP message indicating the telephone number of the called party. The ITG initiates the call on the public telephone network, via the long distance link,

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  using the standard procedures of the long distance connection. This involves sending the registration number of the calling party to the network so that the correct billing procedures can be performed. A gateway is set up simultaneously on the network, so that the computer user can hear the current ringing tones (ringing / busy) sent by the network. An "end-to-end" link is established by the telephone network when

the subscriber answers the call.

  The deyrit system thus offers significant advantages over the prior art in that it enables effective voice communication between users of computers connected to the Internet and telephone users.

PSTN classics.

  The system has been described with reference to speech signals, but it works, of course, with other signals that can be routed on the radio.

  PSTN, like fax or even data signals.

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Claims (12)

REVENDICATTONS   An apparatus for establishing telephone communications between a packet switching network carrying data packets, and a switched network carrying telephone signals, comprising: a first interface unit for connection to the switched network; (A second interface unit for connection to the packet switching network; means for receiving signals at said first interface and for converting them into data packets for transmission over the packet switching network and vice versa. and processing means for determining the destination information from the signals or data packets from the aforesaid first network, and establishing the communication at the destination address on the aforesaid second network based on   of said destination information.   Apparatus according to claim 1, characterized in that said first interface unit comprises a TCP / IP interface unit for sending and receiving data packets on the packet switching network, and wherein said second interface unit is a telephone line interface for connection to the   public switched telephone network. - 17 -   Apparatus according to claim 2, further comprising a messaging system for sending and receiving control messages to said interface units under the control of said processing means. Apparatus according to claim 3, further comprising a circuit switching matrix connected between said first and second interface units.   An apparatus according to claim 1, wherein said processing means establishes communication on the packet switching network from the incoming circuit on said switched network, the addresses of said packet switching network being in one-to-one relationship with the circuits. said switched network.   An apparatus according to claim 1, wherein said processing means extracts the destination information from the called party information conveyed by the   incoming signals on the switched network.   Apparatus according to claim 2, wherein said signals are PCM signals (at pulse code modulation).   Apparatus according to claim 7, wherein said second interface unit is a TDM (Time Division Multiplexing) interface.   time division multiplexing).   9. Method for establishing telephone communications between a network of - 18 -   packet switching carrying data packets, and a switched network carrying telephone signals, comprising the steps of: providing a gateway between the packet switching network and the switched network; receiving data packets from the packet switching network; sending to the gateway a call composition packet for identifying the called party on the switched network; retrieving the called party number from said call dialing packet received by said gateway; the establishment by said gateway of a call to the called number on the switched network; and real-time conversion of the signals from said switched network into data packets for transmission on said packet switching network and vice versa, as and when required. flow of the communication.   The method of claim 9, wherein said packet switching network is a TCP / IP network, and the switched network is the network. public switched telephone.   The method of claim 9, wherein the flow of the communication is - 19 -   controlled by a central processor that runs the   operations by means of command messages.   The method of claim 9, wherein said signals are PCM signals.