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An expert points out that Voice over IP (VoIP) cannot ever be a popular technology unless vendors intercommunicate. Most industry entrants appear to back Session Initiation Protocol (SIP), a specification developed by the Internet Engineering Task Force' (IETF), but even SIP cannot yet all resolve all VoIP challenges, even though experts agree that (Real-Time Transport Protocol) will be the standard for the bearer channel, which carries the voice. However, for users with VoIP, the signaling channel, and VoIP solutions from multiple vendors, VoIP begins to raise questions. The industry has to lock down the standards at the higher levels, says Lawrence Byrd of Avaya. A significant interoperability difficulty will be between VoIP vendors and leading telecommunication carriers, which are also deploying VoIP links, and much will be resolved based on how carriers decide to implement their own VoIP networks. The security issue also looms, says Byrd, because IP telephony protocols intrinsically open many ports in the firewall. For instance, a solution known as Simple Traversal of UDP User Datagram Protocol Through NAT (STUN) opens pinholes in the firewall to allow voice to pass through. Cisco's technical support seems to agree with other experts that there is no easy answer to the complicated issues of interoperability.
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Information Sources, Inc.
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