Session Announcement Protocol," RFC 2974, 2000. Mills, D., "Network Time Protocol (Version 3): Specification, Implementation, and Analysis," RFC 1305, 1992. Schulzrinne, H., et al., "RTP: A Transport Protocol for Real-Time Applications," RFC 3550, 2003. Schulzrinne, H., "RTP Profile for Audio and Video Conferences with Minimal Control," RFC 3550, 2003. Duric, A., and S. Anderson, "RTP Payload Format for iLBC Speech," IETF Internet- Draft, Work in Progress, March 2003. Rosenberg, J., and H. Schulzrinne, "An Offer/Answer Model with Session Description Protocol (SDP)," RFC 3264, 2002. Johnston, A., and R. Sparks, "SDP Offer Answer Examples," IETF Internet-Draft, Work in Progress, June 2003. Kent, S., and R. Atkinson, "Security Architecture for the Internet Protocol," RFC 2401, 1998. Related Protocols Anttalainen, T., Introduction to Telecommunications Network Engineering, Norwood, MA, Artech House, 1999. [11] Schaphorst, R., Videoconferencing and Videotelephony: Technology and Standards, 2nd ed., Norwood, MA: Artech House, 1999. [12] Sjoberg, J., et al., "Real-Time Transport Protocol Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) Audio Codecs," RFC 3267, June 2002. Vermuri, A., and J. Peterson, "Session Initiation Protocol for Telephones (SIP-T): Con- text and Architectures," RFC 3372, 2002. Camarillo, G., et al., "Integrated Services Digital Network (ISDN) User Part (ISUP) to Session Initiation Protocol (SIP) Mapping," RFC 3398, 2002. Elwell, J., et al., "Interworking between SIP and QSIG," IETF Internet-Draft, Work in Progress, April 2003. [16] Johnston, A., et al., "Session Initiation Protocol PSTN Call Flows," IETF Internet-Draft, Work in Progress, April 2003. Zimmerer, E., et al., "MIME Media Types for ISUP and QSIG Objects," RFC 3204, December 2001. [18] UPnP specifications are available at http://www.upnp.org. Steinfeld, E. F., "Devices That Play Together, Work Together," EDN Magazine, Septem- ber 2001, pp. 65-70. Comparison to H.323 This cha