Also known as middleware or session management, the approach is consistent with one emerging vision of the new architecture.

At Enterprise Connect last month, one of our largest-drawing sessions was entitled, "The Post-PBX Platform," and our opening General Session featured end users discussing the question, "Is There a New Model for Enterprise Communications?"

There's no industry consensus (yet) on what comes after the PBX, but a strong contender is the "communications middleware" concept that Zeus laid out in this post-Enterprise Connect blog post. The poster child for this vision has been Avaya, with its ACE middleware for knitting together diverse elements and vendor products into a multimedia communications platform. Now Alcatel-Lucent has announced a product suite, OpenTouch, that seems to reinforce the emerging "communications middleware" vision.

Alcatel's Craig Walker, who briefed me on today's OpenTouch announcement, hastened to draw distinctions between OpenTouch and ACE. We'll get to those in a bit. But from a high level, it's clear that ALU is aiming to do much the same thing. In the schematic below, OpenTouch is the purple layer, what ALU is calling the "conversation layer" of the stack:

The schematic shows, in the layer below the purple, "Federation Services" using SIP to link the legacy ALU OmniPCS ("OXE") with "Other PBXs," which is the investment-protection story for middleware. The purple layer abstracts the applications at the top from the devices they run on, shown at bottom--so that the applications can run on any device, and the whole system can control and dynamically shift sessions or "calls" (loosely defined) among multiple users and media.

ALU uses the terms "conversation" and "session" fairly interchangeably, and "session management" is another concept that we've seen starting to emerge as the new way of thinking about the role that communications platforms will play in the future (see blogs by Zeus here, and by Mykola Konrad here, here, and here. In ALU's case, the division between "User" and "Customer" reflects the company's dual Alcatel/Genesys personnas, serving internal enterprise users as well as external customers via what used to be known as the call center.

Those applications on the top layer also got a fair amount of attention in ALU's announcement today. They include:

* Enterprise IM & presence
* Audio & web conferencing
* Mobility (including the company's MyIC client for tablets)
* Enterprise Video
* Enterprise messaging
* ALU's spiffy MyIC Smart Deskphone . ALU touts this as being "priced as current high-end phones," which Craig Walker translated as 600 Euros or $850 list, which is very high end indeed.

Right now, OpenTouch only scales up to 1,500 users/3,000 devices, but Craig promised that the size would expand to 100K users next year for a true enterprise-scale solution. The Federation Services piece of the system will be released in 4Q11.

So what distinguishes OpenTouch from Avaya ACE? Craig Walker said it's because OpenTouch is "multimedia at the core," and that applications have visibility into the SIP session control. I'll be honest--I don't know how important this is as a differentiator, or even if it is truly something Avaya can't match.

To me, that's the next stage in this industry debate: If at least a significant portion of the vendor world is moving to a middleware vision, how do you decide whose middleware you should commit to, and what does such a commitment even entail? What does it lock you into if you choose OpenTouch over ACE, or vice versa? Will one vendor's multi-PBX-integration function be a major factor to consider among enterprises looking at (as most will be) a long-haul migration? To what extent are these guys still trying to lock you into having to buy their hardware endpoints to make their money?

It's way too early to say that the middleware/session management vision has won, but it seems to be emerging as a significant contender for the role of what comes after the PBX.