At VoiceCon San Francisco last week, I had a chance to speak with Jim Burton about his role as intermediary in the talks between Microsoft and IBM on presence federation. Thinking about that conversation now, I kind of wonder if maybe Jim shouldn't put in his name for Secretary of State in the new administration. Sounds like the negotiations were as complex and delicate as a lot of international diplomacy.As we reported on No Jitter last week, Jim's efforts ultimately succeeded, and Microsoft and IBM now say they are about to make good on their promise to implement inter-domain presence federation between Office Communications Server (OCS) and Lotus Sametime. The work doesn't cover federation between Microsoft's MSN instant messaging and Sametime; MSN is a different division of Microsoft and this would have complicated the process of negotiating interoperability, beyond where it could have gotten done in the seven months the vendors had between VoiceCon Orlando, when they made their commitment, and VoiceCon San Francisco, where they announced success.

I wrote a feature earlier this year about the many obstacles that stand in the way of real, meaningful interoperability in enterprise communications, and last week's Microsoft-IBM announcement addresses just a fraction of this universe. Inter-domain federation can, as the name suggests, link two separate enterprises, which will be useful for the many vendor and partner relationships that large enterprises rely on. But the real critical piece, and the bigger technical challenge, is intra-enterprise federation.

And in that area, all eyes are, once again, on Microsoft. During the VoiceCon session where the inter-domain agreement was announced, IBM's Pat Galvin made it clear that he doesn't feel the job is done. "As far as IBM is concerned," Galvin said, "this process is only half complete.

"I hope that Microsoft starts participating in the intra-domain [work]," Galvin concluded.

IBM, together with Cisco, has taken the lead on trying to solve intra-domain federation, and we were fortunate to have Jonathan Rosenbaum of Cisco on the VoiceCon UC panel. Jonathan, along with Avshalom Houri of IBM, was one of the original co-authors of the IETF draft on intra-domain federation (available here). Not surprisingly, Jonathan joined the call for Microsoft to be more active in the intra-domain effort -- though Microsoft's Eric Swift, probably wisely, refrained from shaking any more hands after the initial introductions were over.

I'm beginning to wonder, however, if the key isn't interoperability, but interworking. Here's what I see as the difference: Interoperability would be the ability to plug any SIP/IP communications device into any other, and have them work together. That'd be terrific, of course, but for all the reasons I outlined in the feature article referenced above, it's more complicated than just presence federation -- and presence federation is pretty complicated, itself.

Interworking would be at once a more modest and potentially more useful goal. For the foreseeable future, we're going to be communicating over diverse overlay networks -- not just a mix of TDM- and IP-based communications in the enterprise, but more importantly, public cellular as well. If an enterprise could tie together all of these diverse components, it could exercise greater control over its cellular costs (and assets, such as phone numbers) and provide more efficient communications to its mobile workforce. The core of such an interworked system is ... well, it's a PBX, probably an IP-PBX.

This isn't as fancy as a presence-enabled, business process-integrated, unified communications system, but I'd argue it has more practical value in the near term. It helps you take costs out your network and serve the immediate needs of your workforce. It lets you slow-roll your TDM-to-IP migration in a tight investment climate, while still opening up collaborative technologies that also save on costs, such as conferencing in all its media.

So interoperability is good if you can get it. Interworking is something you need -- and can get.All eyes are, once again, on Microsoft. During the VoiceCon session where the inter-domain agreement was announced, IBM's Pat Galvin made it clear that he doesn't feel the job is done. "As far as IBM is concerned," Galvin said, "this process is only half complete."