Implementation is all in the details, right? We formulate a broad overview of the goals we want to accomplish, and then work out the nitty-gritty to get it implemented. When it comes to signaling protocols for IP-PBXs, what makes vendors standardize, and then "soup-up" the standard protocol suite into something that can support an enterprise feature set?

I think that it's evident that the major vendors (Avaya, Nortel, Cisco, etc.) have been able to deliver ample feature sets when moving their legacy systems to IP, but it concerns me of just HOW they are doing it.

As an example, think of all of the proprietary IP-based signaling protocols are alive today. A few stand out in my mind: SCCP (Cisco), UNISTIM (Nortel), "modified" versions of H.323 and SIP (Avaya), and MiNET (Mitel). I still don't know if I
can find a major vendor, except for open-source solutions like Asterisk, that is completely non-proprietary.

What's my point? Unless we're deploying for major companies that will simply install one vendor across the board, it is very possible that our infrastructures at different geographic locations simply use different vendors for their PBXs - IP or not! This, along with a sometimes significant invested cost in these existing systems, make it hard to integrate and network systems of different vendors together. Simply imagine trying to interconnect voice platforms from Avaya, Cisco, Nortel, and Digium Asterisk, all together. Without a lot of "hacks" on each system, we won't be seeing a seamless dialplan. I just don't believe it will work (well, that is).

The Internet is littered with excerpts of panicked implementers trying to tie together their CallManager in Boston and their Avaya MultiVantage in Seattle using what should be a standards-based trunking protocol, for example. So, can vendors' claims of "standards-based" compliance be trusted?

So, here's my question. Should we as customers be demanding truly interoperable products from our VoIP vendors? As the vendors' feature sets become more complex, and their proprietary protocols are developed further away from standards, should we be alarmed? Frankly, as most VoIP platforms are still quite new, this seems to be the time to encourage standards-based development. Why not resolve the question now, instead of waiting another 10 years?

Secondly, I'll take a devil's advocate position. We NEED modifications to protocols like SIP, because the simply don't deliver the feature set that implementers need, and users demand. For example, shared and bridged line appearances, support for switchboard-type call handling, etc.

What do you think? Functionality or standards and ensured compatibility?