Telecommunications system

• US 6,584,098 B1
• Filed: 09/02/1999
• Issued: 06/24/2003
• Est. Priority Date: 09/04/1997
• Status: Expired due to Term

• Current Assignee: British Telecommunications PLC (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Dutnall, Stephen
• Primary Examiner(s): Yao, Kwang Bin
• Application Number:
  US09/142,146
• Time in Patent Office: 1,391 Days
• Field of Search: 370/352, 370/353, 370/354, 370/355, 370/356, 370/357, 370/389, 370/392, 370/401, 370/402, 370/403, 370/404, 370/405, 370/406, 370/235, 370/236, 370/237, 370/238, 370/466, 379/93.01, 379/88.17, 379/219, 379/220, 379/221, 709/238, 709/239
• US Class Current: 370/354
• CPC Class Codes: H04L 12/5692 Selection among different networks
• CPC Class Codes: H04L 12/6418 Hybrid transport
• CPC Class Codes: H04L 2012/6443 Network Node Interface, e.g. Routing, Path finding
• CPC Class Codes: H04L 2012/6472 Internet
• CPC Class Codes: H04L 2012/6475 N-ISDN, Public Switched Telephone Network [PSTN]
• CPC Class Codes: H04L 2012/6486 Signalling Protocols
• CPC Class Codes: H04M 7/0057 Services where the data services network provides a telephone service in addition or as an alternative, e.g. for backup purposes, to the telephone service provided by the telephone services network
• CPC Class Codes: H04W 76/10 Connection setup
• CPC Class Codes: H04W 88/16 Gateway arrangements

Abstract

A system for carrying packetized voice and other delay-intolerant traffic, for example, a voice call for transmission over the Internet, over a circuit switched connection when such a connection is available. Incoming packets from a packet data network are identified by a gateway node as having voice characteristics and diverted to travel over a bridge to a circuit-switched network to a terminal, instead of a packet network. This reduces the load on the packet network, which is less suited to voice-type calls than is the circuit-switched network. In the reverse direction, suitable packets generated by the terminal may be routed to the gateway node by way of the circuit-switched network under the control of the terminal itself, or under the control of the network'"'"'s interface with the terminal, either under the control of the gateway node or autonomously.

Claims

1. A method of selecting routing for a corruption-intolerant or delay-intolerant call type between a terminal and a packet-switching gateway such that a corruption-intolerant call is routed by a packet-switching system and a delay-intolerant call is routed by a circuit-switched system to or from the packet-switched gateway, wherein the presence or absence of a data protocol specific to one of the types of call is recognized and the routing between the gateway and terminal selected accordingly, and wherein the gateway detects the type of destination terminal to which the call is to be transmitted, and selects a first mode of operation in which the protocol is retained in the transmission, or a second mode of operation in which the protocol is removed, according to the destination type.

2. A method according to claim 1, comprising the step of intercepting packetized call set-up data, identifying whether the said protocol is incorporated in the packet-based call, and if it has been so incorporated, switching the call from a packet-based system to a circuit-switched system.

3. A method according to claim 1, wherein the destination of a call is identified from an address header of the first packet of a call, a switched circuit is opened between the gateway and the destination, and subsequent packets having the same header are then similarly routed over the switched circuit, which is maintained until the end of the message.

4. A method according to claim 1 wherein if a packet received by the packet-switching gateway over a circuit-switched system is for onward transmission to another destination served by the same circuit-switched system, the call is redirected to the destination without passing through the packet-switching network, thus making the call circuit-switched throughout.

5. Apparatus for routing corruption-intolerant and delay-intolerant calls between a terminal and a packet-switching gateway such that a corruption-intolerant call is routed by a packet-switching system and a delay-intolerant call is routed by a circuit-switched system to or from the packet-switched gateway, the apparatus comprising means for recognizing the presence or absence of a data protocol contained in a data protocol contained in a data packet of the call, and means for routing the call between the gateway and the terminal accordingly;

means for detecting the type of destination terminal to which the call is to be transmitted; and

means for selecting a first mode of operation in which the protocol is retained in the transmission, or a second mode of operation in which the protocol is removed according to the destination type detected.

6. An apparatus according to claim 5, comprising means for intercepting packetized call set-up and identifying whether the protocol is incorporated in the packet-based call, and means for switching calls incorporating such protocols from a packet-switched system to a circuit-switched system.

7. A packet switching gateway according to claim 5, further comprising:

a routing apparatus, the routing apparatus including means for identifying packets received over a circuit-switched system whose destinations are other destinations served by the same circuit-switched system; and

redirection means for transmitting said packets received over said circuit-switched system to the destination without passing through the packet-switching network, thus making the call circuit-switched throughout.

8. A packet switching gateway according to claim 7, wherein the routing apparatus comprises means for identifying the destination of a call from an address header of the first packet of a call;

means for opening a switched circuit between the gateway and the destination, and maintaining the circuit for the duration of the message; and

means for routing subsequent packets having the same header over the same circuit.

9. A method of routing calls between a terminal and a packet-switching gateway, the method comprising:

routing a corruption-intolerant call by a packet-switching system;

routing a delay-intolerant call by a circuit-switched system to or from the packet-switched gateway, wherein the presence or absence of a data protocol specific to call type is recognized and the routing between the gateway and terminal selected accordingly; and

wherein the packet-switched gateway detects the type of a destination terminal to which a call is to be transmitted, and selects a first mode of operation in which a protocol is retained in the transmission, or a second mode of operation in which the protocol is removed, according to the destination type.

10. An apparatus for routing corruption-intolerant and delay-intolerant calls between a terminal and a packet-switching gateway, the apparatus comprising:

means for routing a corruption-intolerant call by a packet-switching system;

means for routing a delay-intolerant call by a circuit-switched system;

means for recognizing the presence or absence of a data protocol contained in a data protocol contained in a data packet of the call;

means for routing the call between the gateway and the terminal;

means for detecting the type of a destination terminal to which a call is to be transmitted, and

means for selecting a first mode of operation in which a protocol is retained in the transmission, or a second mode of operation in which the protocol is removed, according to the destination terminal.