Using PSTN Reachability to Verify VoIP Call Routing Information

• US 20090022149A1
• Filed: 07/20/2007
• Published: 01/22/2009
• Est. Priority Date: 07/20/2007
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Wing, Daniel G., Rosenberg, Jonathan, Jennings, Cullen F.
• Granted Patent: US 8,199,746 B2
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04L 65/1036 at the edge
• CPC Class Codes: H04L 65/1069 Session establishment or de-establishment
• CPC Class Codes: H04M 2203/551 Call history recording a computer conference H04L12/1831
• CPC Class Codes: H04M 3/5125 with remote located operators
• CPC Class Codes: H04M 3/5232 Call distribution algorithms
• 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: H04M 7/006 Networks other than PSTN/ISDN providing telephone service, e.g. Voice over Internet Protocol (VoIP) , including next generation networks with a packet-switched transport layer H04L65/00 takes precedence; aspects not specific to the type of network H04M3/00; special services in those networks H04M3/42
• CPC Class Codes: H04M 7/0063 where the network is a peer-to-peer network

Abstract

A system for verifying VoIP call routing information. In particular implementations, a method includes verifying one or more Voice-over-Internet-Protocol (VoIP) call agents for respective destination telephone numbers based on demonstrated knowledge of previous public switched telephone network (PSTN) calls to the respective destination telephone numbers; receiving a call initiation message identifying a destination telephone number; and conditionally initiating a call over a VoIP network to a target VoIP call agent, or over a circuit switched network, based on whether the target VoIP call agent has been verified for the destination telephone number identified in the call initiation message.

Claims

1. A method comprising:

verifying one or more Voice-over-Internet-Protocol (VoIP) call agents for respective destination telephone numbers based on demonstrated knowledge of previous public switched telephone network (PSTN) calls to the respective destination telephone numbers;

receiving a call initiation message identifying a destination telephone number; and

conditionally initiating a call over a VoIP network to a target VoIP call agent, or over a circuit switched network, based on whether the target. VoIP call agent has been verified for the destination telephone number identified in the call initiation message.

2. The method of claim 1 wherein the verifying comprises:

recording one or more attributes of one or more of the previous PSTN calls;

transmitting a query for proof of awareness of one or more of the PSTN call attributes for a destination telephone number to a VoIP call agent; and

receiving a response to the query from the VoIP call agent.

3. The method of claim 1 further comprising querying a peer-to-peer network to discover the network address of a VoIP call agent associated with the destination phone number.

4. The method of claim 3 further comprising caching results of the querying the peer-to-peer network.

5. The method of claim 3 wherein one or more members of the peer-to-peer network include VoIP call agents.

6. The method of claim 1 further comprising querying a central server to determine a network address of a VoIP call agent associated with the destination phone number.

7. The method of claim 6 further comprising caching results of the querying the central server.

8. The method of claim 1 further comprising

converting the destination telephone number into a hierarchically structured identifier;

and

querying a hierarchical network of servers to determine a network address of a VoIP call agent associated with the destination telephone number.

9. The method of claim 8 wherein the hierarchical network of servers is a Domain Name System.

10. The method of claim 8 further comprising constructing the hierarchical structured identifier based at least in part on an Electronic Numbering (ENUM) protocol.

11. The method of claim 1 further comprising

responsive to receiving the call initiation message identifying a destination telephone number, accessing a cache of Voice over Internet Protocol (VoIP) call routing information, wherein the cache comprises a plurality of entries, and wherein each entry comprises a telephone number and a network address of a corresponding VoIP call agent, or a prefix and a network address of a corresponding VoIP call agent;

searching the cache, using the destination telephone number, for a matching entry; and

if a matching entry is found in the cache, making a VoIP call to the VoIP call agent corresponding to the destination phone number.

12. The method of claim 11 further comprising

conditionally adding VoIP call routing information for one or more VoIP call agents to the cache based on the verifying step.

13. The method of claim 11 further comprising

if a matching phone number is not found in the cache, accessing a registry of VoIP call routing information, wherein the registry comprises a plurality of entries, and wherein each entry comprises a telephone number prefix and a network address of a corresponding VoIP call agent;

searching the registry, using the destination telephone number, for a matching entry;

making a public switched telephone network (PSTN) call to the destination phone number;

verifying the VoIP call agent based on one or more attributes of the PSTN call; and

conditionally adding the VoIP call routing information of the matching entry from the registry to the cache based on the verifying step.

14. The method of claim 13 wherein the verifying comprises:

recording one or more attributes of the PSTN call;

transmitting a query for the one or more PSTN call attributes to the VoIP call agent; and

receiving a response to the query for the one or more PSTN call attributes from the VoIP call agent.

15. The method of claim 2 wherein the verifying comprises:

mapping the respective attributes of the previous PSTN calls to a username and password; and

using an authentication protocol to verify that a VoIP call agent knows the password for a given username.

16. The method of claim 15 wherein the username is based at least in part on a point in time during the PSTN call, and wherein the password is based at least in part on a start time or a stop time of the PSTN call.

17. The method of claim 15 wherein the username is based at least in part on a caller ID of the PSTN call, and wherein the password is based at least in part on a start time or a stop time of the PSTN call.

18. The method of claim 15 wherein the username is based at least in part on a portion of a signature of the PSTN call, and wherein the password is based at least in part on a portion of the signature of the PSTN call.

19. The method of claim 2 wherein the PSTN call attributes comprise one or more of a start call time, an end call time, a caller identification, a call length, and a call signature.

20. The method of claim 2 wherein the PSTN call attributes comprise a call signature, wherein the call signature is based on one or more of frequency spectrum analysis, silence detection, and a password.

21. The method of claim 2 wherein the verifying step is performed after a PSTN call ends.

22. The method of claim 2 wherein the verifying step is performed before a PSTN call ends.

23. The method of claim 1 further comprising augmenting the verifying step to cause a revalidation of a telephone number.

24. The method of claim 23 wherein the revalidation Is performed after a predefined period of time.

25. The method of claim 23 wherein the revalidation is performed periodically.

26. The method of claim 23 wherein the revalidation is performed randomly.

27. Logic encoded in one or more tangible media for execution and when executed operable to;

verify one or more Voice-over-Internet-Protocol (VoIP) call agents for respective destination telephone numbers based on demonstrated knowledge of previous public switched telephone network (PSTN) calls to the respective destination telephone numbers;

receive a call initiation message identifying a destination telephone number; and

conditionally initiate a call over a VoIP network to a target VoIP call agent, or over a circuit switched network, based on whether the target VoIP call agent has been verified for the destination telephone number identified in the call initiation message.

28. An apparatus, comprising

one or more network interfaces;

a memory;

one or more processors; and

a call agent application physically stored in the memory comprising computer-readable instructions operative to cause the one or more processors to;

verify one or more Voice-over-Internet-Protocol (VoIP) call agents for respective destination telephone numbers based on demonstrated knowledge of previous public switched telephone network (PSTN) calls to the respective destination telephone numbers;

receive a call initiation message identifying a destination telephone number; and

conditionally initiate a call over a VoIP network to a target VoIP call agent, or over a circuit switched network, based on whether the target VoIP call agent has been verified for the destination telephone number identified in the call initiation message.