Hybrid TDM and ATM voice switching central office and method of completing inter-office calls using same

• US 6,930,998 B1
• Filed: 12/07/1998
• Issued: 08/16/2005
• Est. Priority Date: 12/07/1998
• Status: Expired due to Fees

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Lakhani, Faizel, Sylvain, Dany
• Primary Examiner(s): Pezzlo, John
• Assistant Examiner(s): Tsegaye, Saba
• Application Number:
  US09/206,277
• Time in Patent Office: 2,444 Days
• Field of Search: 370352-356, 370/395.1, 370/395.52, 370/395.61, 370400-401, 370465-466
• US Class Current: 370/352
• CPC Class Codes: H04L 12/6402 Hybrid switching fabrics
• CPC Class Codes: H04L 2012/5618 Bridges, gateways [GW] or interworking units [IWU]
• CPC Class Codes: H04L 2012/563 Signalling, e.g. protocols, reference model
• CPC Class Codes: H04L 2012/5663 Support of N-ISDN
• CPC Class Codes: H04L 2012/6475 N-ISDN, Public Switched Telephone Network [PSTN]
• CPC Class Codes: H04L 2012/6481 Speech, voice
• CPC Class Codes: H04L 49/606 Hybrid ATM switches, e.g. ATM&STM, ATM&Frame Relay or ATM&IP
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections
• CPC Class Codes: H04Q 2213/1338 Inter-exchange connection
• CPC Class Codes: H04Q 3/0025 Provisions for signalling

Abstract

A hybrid central office for serving a plurality of subscriber lines while serving as a virtual access tandem to a subnetwork of central offices having a connection to an ATM backbone network is described. The hybrid central office includes a computing module having a messaging interface to the ATM network, an inter-working trunk interface to the ATM network and a trunk connection to the PSTN. The hybrid central office serves as a tandem switch for other central offices connected to the subnetwork. Other central offices are preferably connected to the subnetwork by a signal large trunk group. All inter-office call routing is therefore handled by the hybrid central office. The hybrid central office also provides a gateway to the PSTN. Inter-office calls originated and terminated within the subnetwork are set up by the virtual access tandem but after call set up, the virtual access tandem is not involved in the call. The advantage is the utilization of spare processing capacity in a central office to off-load inter-office trunking congestion, as well as a significant reduction in trunking maintenance costs.

Claims

1. A telephony switch comprising:

a switching fabric;

a first interface adapted to connect the switching fabric to a packet fabric;

a computing module operatively associated with the switching fabric and the first interface and capable of establishing calls through the switching fabric, the packet fabric, and the switching fabric and the packet fabric, the computing module adapted to;

receive a call request for establishing a call between an originating endpoint and a terminating endpoint;

based on the originating endpoint and the terminating endpoint, determine a select one of the switching fabric, the packet fabric, and the switching fabric and the packet fabric through which to establish the call; and

establish the call through the select one of the switching fabric, the packet fabric, and the switching fabric and the packet fabric, wherein when at least one of the originating and terminating endpoints is coupled to the packet fabric, the call is established in part by sending a message to one of the at least one of the originating and the terminating endpoints to instruct the one of the at least one of the originating and terminating endpoints to enable communication for the call through the packet fabric.

2. The switch of claim 1 further comprising a second interface adapted to connect the switching fabric to a public switched telephone network (PSTN).

3. The switch of claim 2 wherein when the originating endpoint and the terminating endpoint are coupled to the PSTN, the computing module is adapted to establish the call through the switching fabric.

4. The switch of claim 3 wherein when the originating endpoint and the terminating endpoint are both coupled to the packet fabric, the computing module is adapted to establish the call through the packet fabric.

5. The switch of claim 4 wherein when the originating endpoint is coupled to the PSTN and the terminating endpoint is coupled to the packet fabric, the computing module is adapted to establish the call through the switching fabric and the packet fabric via the first interface.

6. The switch of claim 5 wherein when the originating endpoint is coupled to the packet fabric and the terminating endpoint is coupled to the PSTN, the computing module is adapted to establish the call through the packet fabric and the switching fabric via the first interface.

7. The switch of claim 2 wherein the computing module is further adapted to establish an inter-working bridge across the switching fabric for the call when the originating endpoint is coupled to the packet fabric and the terminating endpoint is coupled to the PSTN and when the originating endpoint is coupled to the PSTN and the terminating endpoint is coupled to the packet fabric.

8. The switch of claim 7 wherein the first interface is further adapted to support the inter-working bridge across the switching fabric.

9. The switch of claim 8 wherein the first interface is further adapted to generate an application instance for the inter-working bridge.

10. The switch of claim 2 wherein the computing module operates to minimize the number of calls established through the switching fabric and the packet fabric.

11. The switch of claim 2 wherein the computing module is further adapted to formulate and send fabric control messages used to establish virtual connections in the packet fabric for transferring bearer traffic associated with the call when the originating endpoint, terminating endpoint, or the originating and terminating endpoints are coupled to the packet fabric.

12. The switch of claim 1 wherein the computing module is adapted to receive the call request via a signaling network.

13. The switch of claim 12 wherein the signaling network is a common channel signaling network.

14. The switch of claim 1 wherein the computing module comprises a signaling interface coupled to the packet fabric, the signaling interface adapted to receive call signaling messages from and send call signaling messages to the originating endpoint, the terminating endpoint, or the originating endpoint and the terminating endpoint through the packet fabric.

15. The switch of claim 1 wherein the packet fabric is a backbone network.

16. The switch of claim 1 wherein when both the originating and terminating endpoints are coupled to the packet fabric, the computing module is further adapted to send a message to one of the originating and the terminating endpoints, thereby instructing the one of the originating and terminating endpoints to communicate with the other of the originating and terminating endpoints to enable communication for the call through the packet fabric.

17. The switch of claim 1 wherein when the originating endpoint is coupled to the PSTN and the terminating endpoint is coupled to the packet fabric, the computing module is further adapted to send a message to the terminating endpoint, thereby instructing the terminating endpoint to communicate with the first interface to enable communication for the call through the packet fabric.

18. The switch of claim 1 wherein when the originating endpoint is coupled to the packet fabric and the terminating endpoint is coupled to the PSTN, the computing module is further adapted to send a message to the originating endpoint, thereby instructing the originating endpoint to communicate with the first interface to enable communication for the call through the packet fabric.

19. A telephony switch comprising:

means for interfacing a switching fabric in the telephony switch to a packet fabric;

means for establishing calls through the switching fabric, the packet fabric, and the switching fabric and the packet fabric comprising;

means for receiving a call request for establishing a call between an originating endpoint and a terminating endpoint;

means for determining a select one of the switching fabric, the packet fabric, and the switching fabric and the packet fabric through which to establish the call based on the originating endpoint and the terminating endpoint; and

the means for establishing for adapted to establish the call through the select one of the switching fabric, the packet fabric, and the switching fabric and the packet fabric, wherein when at least one of the originating and terminating endpoints is coupled to the packet fabric, the call is established in part by sending a message to one of the at least one of the originating and the terminating endpoints, thereby instructing the one of the at least one of the originating and terminating endpoints to enable communication for the call through the packet fabric.

20. The switch of claim 19 further comprising a means for interfacing the switching fabric to a public switched telephone network (PSTN).

21. The switch of claim 20 wherein when the originating endpoint and the terminating endpoint are coupled to the PSTN, the means for establishing the call establishes the call through the switching fabric.

22. The switch of claim 21 wherein when the originating endpoint and the terminating endpoint are both coupled to the packet fabric, the means for establishing the call establishes the call through the packet fabric.

23. The switch of claim 22 wherein when the originating endpoint is coupled to the PSTN and the terminating endpoint is coupled to the packet fabric, the means for establishing the call establishes the call through the switching fabric and the packet fabric via the first interface.

24. The switch of claim 23 wherein when the originating endpoint is coupled to the packet fabric and the terminating endpoint is coupled to the PSTN, the means for establishing the call establishes the call through the packet fabric and the switching fabric via the first interface.

25. The switch of claim 20 wherein means for establishing the call is further adapted to establish an inter-working bridge across the switching fabric for the call when the originating endpoint is coupled to the packet fabric and the terminating endpoint is coupled to the PSTN and when the originating endpoint is coupled to the PSTN and the terminating endpoint is coupled to the packet fabric.

26. The switch of claim 25 wherein the means for interfacing the switching fabric to the packet fabric is further adapted to support the inter-working bridge across the switching fabric.

27. The switch of claim 26 wherein the means for interfacing the switching fabric to the packet fabric is further adapted to generate an application instance for the inter-working bridge.

28. The switch of claim 20 wherein the means for establishing the call operates to minimize the number of calls established through the switching fabric and the packet fabric.

29. The switch of claim 20 wherein the means for establishing the call is further adapted to formulate and send fabric control messages used to establish virtual connections in the packet fabric for transferring bearer traffic associated with the call when the originating endpoint, terminating endpoint, or the originating and terminating endpoints are coupled to the packet fabric.

30. The switch of claim 19 wherein the means for receiving the call request receives the call request via a signaling network.

31. The switch of claim 30 wherein the signaling network is a common channel signaling network.

32. The switch of claim 19 wherein the means for establishing the call further comprises a means for communicating with the packet fabric, wherein the means for communicating with the packet fabric is adapted to receive call setup messages from and send call setup messages to the originating endpoint, the terminating endpoint, or the originating endpoint and the terminating endpoint through the packet fabric.

33. The telephony switch of claim 19 wherein the packet fabric is a backbone network.

34. The telephony switch of claim 19 wherein when both the originating and terminating endpoints are coupled to the packet fabric, the means for establishing calls is further adapted to send a message to one of the originating and the terminating endpoints, thereby instructing the one of the originating and terminating endpoints to communicate with the other of the originating and terminating endpoints to enable communication for the call through the packet fabric.

35. The telephony switch of claim 19 wherein when the originating endpoint is coupled to the PSTN and the terminating endpoint is coupled to the packet fabric, the means for establishing calls is further adapted to send a message to the terminating endpoint, thereby instructing the terminating endpoint to communicate with the first interface to enable communication for the call through the packet fabric.

36. The method of claim 19 wherein when the originating endpoint is coupled to the packet fabric and the terminating endpoint is coupled to the PSTN, the means establishing calls is further adapted to send a message to the originating endpoint, thereby instructing the originating endpoint to communicate with the first interface to enable communication for the call through the packet fabric.

37. A method of establishing a call between an originating endpoint and a terminating endpoint through a hybrid switch capable of establishing calls through a switching fabric, a packet fabric, and a switching fabric and a packet fabric, the method comprising:

interfacing a switching fabric in the telephony switch to a packet fabric and a public switched telephone network (PSTN) using a first interface;

receiving a call request for establishing a call between an originating endpoint and a terminating endpoint;

determining a select one of the switching fabric, the packet fabric, and the switching fabric and the packet fabric through which to establish the call based on the originating endpoint and the terminating endpoint; and

establishing the call through the select one of the switching fabric, the packet fabric, and the switching fabric and the packet fabric;

wherein when at least one of the originating and terminating endpoints is coupled to the packet fabric, establishing the call comprises sending a message to one of the at least one of the originating and the terminating endpoints, thereby instructing the one of the at least one of the originating and terminating endpoints to enable communication for the call through the packet fabric.

38. The method of claim 37 wherein when the originating endpoint is coupled to the PSTN and the terminating endpoint is coupled to the PSTN, the establishing step comprises establishing the call through the switching fabric.

39. The method of claim 38 wherein when the originating endpoint is coupled to the PSTN and the terminating endpoint is coupled to the packet fabric, the establishing step comprises establishing the call through the switching fabric and the packet fabric.

40. The method of claim 39 wherein when the originating endpoint is coupled to the packet fabric and the terminating endpoint is coupled to the PSTN fabric, the establishing step comprises establishing the call through the switching fabric and the packet fabric.

41. The method of claim 40 wherein when the originating endpoint is coupled to the packet fabric and the terminating endpoint is coupled to the packet fabric, the establishing step comprises establishing the call through the packet fabric.

42. The method of claim 37 wherein the receiving the call request step comprises receiving the call request via a signaling network.

43. The method of claim 37 wherein the establishing the call step comprises establishing an inter-working bridge across the switching fabric for the call when the originating endpoint is coupled to the packet fabric and the terminating endpoint is coupled to the PSTN and when the originating endpoint is coupled to the PSTN and the terminating endpoint is coupled to the packet fabric.

44. The method of claim 37 wherein the establishing the call step comprises receiving call setup messages from and sending call setup messages to the originating endpoint, the terminating endpoint, or the originating endpoint and the terminating endpoint through the packet fabric.

45. The method of claim 37 wherein the establishing the call step minimizes the number of calls established through the switching fabric and the packet fabric.

46. The method of claim 37 wherein the establishing the call step comprises formulating and sending fabric control messages used to establish virtual connections in the packet fabric for transferring bearer traffic associated with the call when the originating endpoint, terminating endpoint, or the originating and terminating endpoints are coupled to the packet fabric.

47. The method of claim 37 wherein the packet fabric is a backbone network.

48. The method of claim 37 wherein when both the originating and terminating endpoints are coupled to the packet fabric, establishing the call further comprises sending a message to one of the originating and the terminating endpoints, thereby instructing the one of the originating and terminating endpoints to communicate with the other of the originating and terminating endpoints to enable communication for the call through the packet fabric.

49. The method of claim 37 wherein when the originating endpoint is coupled to the PSTN and the terminating endpoint is coupled to the packet fabric, establishing the call further comprises sending a message to the terminating endpoint, thereby instructing the terminating endpoint to communicate with the first interface to enable communication for the call through the packet fabric.

50. The method of claim 37 wherein when the originating endpoint is coupled to the packet fabric and the terminating endpoint is coupled to the PSTN, establishing the call further comprises send a message to the originating endpoint, thereby instructing the originating endpoint to communicate with the first interface to enable communication for the call through the packet fabric.