System and method for determining trust for SIP messages

1. A non-transitory computer readable medium containing instructions that when executed by a processor cause the processor to perform operations comprising:

receiving, at a user agent (UA) from a network node, a message containing a trust indicator, wherein the network node is in an IP (Internet Protocol) Multimedia Subsystem (IMS) network;

determining, at the UA, whether the trust indicator matches trust information stored in the UA;

when the trust indicator matches trust information stored in the UA, the UA performing all actions typically associated with receipt of the message; and

when the trust indicator does not match trust information stored in the UA, the UA refraining from performing at least one action typically associated with receipt of the message.

2. The non-transitory computer readable medium of claim 1 , wherein the trust indicator is a Uniform Resource Identifier (URI) of the network node that sent the message.

3. The non-transitory computer readable medium of claim 1 , wherein the trust indicator is conveyed to the UA as a value representative of a sender of the message, and wherein the UA knows the value could be provided only by a trusted sender.

4. The non-transitory computer readable medium of claim 1 , wherein the trust information is provided to the UA in a message sent to the UA in response to a registration request made by the UA.

5. The non-transitory computer readable medium of claim 1 , wherein the trust information is provided to the UA as information related to a route over which a registration request made by the UA was routed.

6. The non-transitory computer readable medium of claim 5 , wherein the information related to the route is included in at least one field in at least one of:

a SIP Path header;

a SIP Service-Route header; and

a new SIP header defined for including the information.

7. The non-transitory computer readable medium of claim 1 , wherein refraining from performing at least one action typically associated with receipt of the message includes at least one of:

denying the message;

discarding the message;

terminating the message;

returning an error message related to the message; and

not performing undesirable actions associated with the message and performing other actions associated with the message.

8. A non-transitory computer readable medium containing instructions that when executed by a processor enable the processor to perform operations comprising:

receiving a SIP request, at a network node from a user equipment (UE) of a user, wherein the network node is in a Session Initiation Protocol (SIP) based network;

responsive to receiving the SIP request, attempting to retrieve a user's profile from a home subscriber server; and

responsive to detecting a failure to retrieve the user's profile from the home subscriber server, sending a first SIP response to the UE of the user, the first SIP response being a SIP server timeout message, the SIP server timeout message including an indication indicating support for restoration procedures, the SIP server timeout message further including at least a first field set to a value equal to a value provided in a Service-Route header field, the Service-Route header field included in a second SIP response to a SIP REGISTER request of the UE, the SIP REGISTER request sent by the UE of the user,

wherein the value sent in the SIP server timeout message includes a Uniform Resource Identifier (URI) representative of the network node in the SIP-based network, the value being usable by the UE to compare with the value provided in the Service-Route header field.

9. The non-transitory computer readable medium of claim 8 , wherein the URI is a SIP URI.

10. The non-transitory computer readable medium of claim 8 , wherein the first field comprises a P-Asserted-Identify header field.

11. The non-transitory computer readable medium of claim 8 , wherein the network node is a Serving Call Session Control Function (S-CSCF).

12. The non-transitory computer readable medium of claim 8 , wherein the network node is a network node within a trust domain.

13. The non-transitory computer readable medium of claim 8 , wherein the SIP request from the UE comprises one of an initial request for a dialog and a request for a standalone transaction.

14. The non-transitory computer readable medium of claim 8 , wherein the attempt to retrieve the user's profile from the home subscriber server is based upon one of: the network node does not have the user's profile, or does not trust data that it has.

15. A non-transitory computer readable medium containing instructions that when executed by a processor cause the processor to perform operations comprising:

receiving at a user agent (UA) a message, the message being a server timeout message, the server timeout message including at least a first field set to a value equal to a value received in a second field during a first registration; and

initiating restoration procedures by performing a second registration in response to receiving the server timeout message.

16. The non-transitory computer readable medium of claim 15 , wherein the value received in the server timeout message is a Session Initiation Protocol (SIP) Uniform Resource Identifier (URI) of a Serving Call Session Control Function (S-CSCF).

17. The non-transitory computer readable medium of claim 15 , wherein the value received in the server timeout message is a SIP URI of a Proxy Call Session Control Function (P-CSCF).

18. The non-transitory computer readable medium of claim 15 , wherein the first field comprises a P-Asserted-Identify header field.

19. The non-transitory computer readable medium of claim 15 , wherein the second field is one of a Service-Route header field and a Path header field.