IP telephony interoperability faces an uphill battle

Attempting to learn lessons from the closed, proprietary systems of the public switched telephone network, next-generation IP telephony product vendors today are struggling to establish interoperability as a tenet of the communications systems of the future.

However, real world examples of true interoperability have yet to be widely demonstrated by the key vendors involved in developing systems for sending voice traffic over packet-based networks.

In a recent demonstration at the IP Telephony Expo in San Diego, approximately 25 companies – including 3Com Corp., Tundo Corp., Agilent Technologies, Lucent Quicknet, and Nx Networks Inc. – attempted to show multivendor interoperability among various IP telephony devices in a convergent network built on the show floor. Although close to 10 of the vendors did achieve connectivity with other vendors’ systems, the majority of companies involved in the ConvergeNet demonstration failed.

Participants and show organizers cited a lack of commitment to the project, problems with equipment, and insufficient preparation. Although most vendors tout interoperability as a key benefit of IP-based communications, proof of such claims are hard to find.

“The industry is talking about interoperability. [Vendors] say they are interoperable but most are not,” said Rich Tehrani, president of Norwalk, Conn.-based publishers TMC, and conference co-chairman. “For this industry to be more legitimate, there needs to be a much greater level of interoperability.”

One analyst agreed that demonstrating interoperability is a necessary step in the growth of packet-based telephony networks.

“Interoperability is going to be crucial [in IP telephony] because it is a fundamental shift away form proprietary schemes of communication where interoperability wasn’t as important,” said Ron Westfall, senior analyst at Current Analysis, in Sterling, Va. “If you want to take advantage of the flexibility that comes with the IP protocol, interoperability is essential.”

According to show organizers and participants, interoperability using H.323, SIP (Session Initiation Protocol), and MGCP (Media Gateway Control Protocol) was illustrated at the show. Among the vendors achieving interoperability success were 3Com, dynamicsoft, and Ubiquity using SIP, and Quicknet, Tundo, Unidata, Active Voice, Agilent and others with H.323.

“Interoperability is a very key issue when you get into IP telephony. There is no way one vendor can own the whole network,” according to Ed Okerson, technical staff member at Quicknet, in Garland, Tex.

H.323 is an IP telephony standard developed by the ITU (International Telecommunications Union) standards body. According to analysts and vendors, although H.323 is widely used by many vendors, newer more scalable standards, such as SIP, are emerging.

Developed by the IETF (Internet Engineering Task Force), SIP has now emerged as the telephony standard for the future. Because SIP was developed by an Internet-oriented standards body, it is more open and easier to work with, according to Arif Ahsan, senior marketing engineer at 3Com in Rolling Meadows, Ill.

“The biggest advantage of SIP is that it is straightforward and easy to develop. The code is easy to write. H.323 is a mess in terms of coding. It is complicated with a lot of signaling,” said Ahsan.

As standards fall into place, vendors must make interoperability a priority now, according to Westfall.

“If you can’t do it at a trade show under controlled circumstances with limited scalability then it begs the question whether interoperability can be parlayed into wide scale networks anytime in the near future,” he said.

“Vendors need to get their act together if they are serious about IP telephony implementations becoming more mature and business savvy,” Westfall added. “The industry understands this has to happen in order for there to be truly a business case for migrating efficiently to a non-circuit switched telephony infrastructure.”