and C. Jennings. 2007. Network Address Translation Behav- ioral Requirements for UDP. RFC 4787, January, http://www.ietf.org/ rfc/rfc4787.txt. Accessed November 15, 2007. [3] Rosemberg, J., et al., 2002. SIP: Session Initiation Protocol. IETF Net- work Working Group, June, http://www.ietf.org/rfc/rfc3261.txt RFC 3261. Accessed November 15, 2007. [4] Ford, B., P. Srisuresh, and D. Kegel. Peer-to-peer Comminucations Across Network Address Translators (NATs). http://www.bford.info/ pub/net/p2pnat/. Accessed November 15, 2007. [5] Rosenberg, J., J. Weinberger, C. Huitema, and R. Mahy. 2003. STUN- Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NATs). RFC 3489, March, http://www.ietf.org/ rfc/rfc3489.txt. Accessed November 15, 2007. [6] Rosenberg, J., R. Mahy, P. Matthews, and D. Wing. 2007. Session Traversl Utilities for (NAT) (STUN). Internet Draft, November 17, http://tools.ietf.org/html/draft-ietf-behave-rfc3489bis-13. [7] Rosenberg, J., 2007. Interactive Connectivity Establishment (ICE): A Protocol for Network Address Translator (NAT) Traversal fro Offer/ Answer Protocols. Internet Draft, October 29, http://tools.ietf.org/ html/draft-ietf-mmusic-ice-19. [8] Multiparty Multimedia Session Control (mmusic), IETF Work- ing Group, http://www.ietf.org/html.charters/mmusic-charter.html. Accessed November 15, 2007. [9] Rosenberg, J., R. Mahy, P. Matthews, and D. Wing. 2007. Traver- sal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Utilities for NAT (TURN). Internet Draft, November 15, http://tools.ietf.org/html/draft-ietf-behave-turn-05. [10] Boulton, C., J. Rosenberg, and G. Camarillo. 2007. Best Cur- rent Practices for NAT traversal for SIP. Internet Draft, July 9, http://tools.ietf.org/html/draft-ietf-sipping-nat-scenarios-07 [11] Rosenberg, J., and H. Schulzrinne. 2003. An Extension to the Session Initiation Protocol (SIP) for Symmetric Response Routing. RFC 3581. August, http://www.ietf.org/rfc/rfc3581.txt C 2009 by Taylor & Francis Group, LLC SIP Handboo