System and method for geographic SIP scaling

1. A method for scaling a session initiation protocol (“SIP”) communication for one or more user agents, the method comprising the steps of:

configuring a domain name system (“DNS”) to identify, via application of at least one of a filter and a rule, a first proxy server from among a plurality of possible proxy servers associated with a common domain to facilitate a SIP communication for a first of the user agents based on contact information for the first user agent;

registering at least a portion of the contact information for the first user agent with the first proxy server, wherein the portion of the contact information for the first user agent is sufficient to effect transmission of the SIP communication between the first proxy server and the first user agent;

registering proxy contact information for the first user agent with a registrar, wherein the proxy contact information for the first user agent includes an indication that the first proxy server is configured to facilitate the SIP communication for the first user agent;

configuring the DNS to identify a second proxy server to facilitate the SIP communication for a second of the user agents based on contact information for the second user agent;

registering at least a portion of the contact information for the second user agent with the second proxy server, wherein the portion of the contact information for the second user agent is sufficient to effect transmission of the SIP communication between the second proxy server and the second user agent;

registering proxy contact information for the second user agent with the registrar, wherein the proxy contact information for the second user agent includes an indication that the second proxy server is configured to facilitate the SIP communication for the second user agent;

requesting the proxy contact information for the second user agent;

transmitting a SIP communication request to the second user agent based on the proxy contact information for the second user; and

establishing the SIP communication based at least in part on a part of the proxy contact information for the second user agent and on a part of the proxy contact information for the first user agent.

2. The method of claim 1 wherein the step of configuring a DNS comprises utilizing a geographic DNS (“geoDNS”) function to identify the first proxy server to facilitate the SIP communication for the first user agent.

3. The method of claim 1 wherein the step of configuring a DNS comprises utilizing an anycast function to identify the first proxy server to facilitate the SIP communication for the first user agent.

4. The method of claim 1 wherein the proxy contact information for the first user agent comprises a direct contact address for the first proxy server.

5. The method of claim 4 wherein the proxy contact information for the first user agent comprises a path header that comprises a direct contact address for the first user agent and an identification of the first proxy server.

6. The method of claim 1 wherein the proxy contact information for the first user agent comprises the portion of the contact information for the first user agent.

7. The method of claim 1 , wherein the contact information for the first user agent comprises a SIP uniform resource identifier associated with the first user agent.

8. The method of claim 1 , wherein the contact information comprises a domain name associated with the first user agent.

9. The method of claim 1 , wherein the first proxy server comprises the second proxy server.

10. A method for facilitating session initiation protocol (“SIP”) communications comprising the steps of:

registering contact information for a first user agent with a first proxy server, wherein the contact information for the first user agent comprises information sufficient to contact the first user agent, and wherein the first proxy server was identified by a domain name system from among a plurality of possible proxy servers associated with a common domain based on at least a portion of the contact information for the first user agent via application of at least one of a filter and a rule;

registering contact information for the first proxy server with a registrar, wherein the contact information for the first proxy server comprises the contact information for the first user agent, an indication that the first proxy server is configured to facilitate SIP communication for the first user agent, and information sufficient to contact the first proxy server;

receiving a request from a second proxy server to establish a SIP communication with the first user agent, wherein the second proxy server is associated with a second user agent;

transmitting the contact information for the first proxy server to the second proxy server if the second proxy server is different from the first proxy server; and

transmitting the contact information for the first user agent to the second proxy server if the second proxy server is the same as the first proxy server.

11. The method of claim 10 further comprising:

receiving a request to initiate a first SIP communication from the first user agent at the first proxy server, wherein the first SIP communication is directed to a second user agent; and

encoding the contact information for the first user agent as a globally routable user agent uniform resource identifier (“GRUU”) for the first user agent.

12. The method of claim 11 further comprising transmitting the GRUU for the first user agent to the second user agent.

13. The method of claim 12 further comprising the step of receiving a response from the second user agent, wherein the response comprises a GRUU for the second user agent.

14. The method of claim 12 further comprising:

establishing a second SIP communication between the second user agent and a third user agent;

transmitting the GRUU for the first user agent to the third user agent in the second SIP communication; and

using the GRUU for the first user agent to establish a third SIP communication between the first user agent and the third user agent.