Peer-to-peer SIP (P2P-SIP) is an implementation of a distributed voice over Internet Protocol (VoIP) or instant messaging communications application using a peer-to-peer (P2P) architecture in which session control between communication end points is facilitated with the Session Initiation Protocol (SIP).
[2][3] P2P application design can improve scalability[4] and survivability in the event of central network outages.
The search key in such a mechanism is the Uniform Resource Identifier (URI) of a user agent.
This URI requires resolution to a particular device or Uniform Resource Locator (URL) that must be performed in real time.
[7] The Internet Engineering Task Force (IETF) is conducting a working group (P2PSIP) that develops standards-track specifications for P2P-SIP.