Q: (from Bill)

I was looking at a telephone system for which they demonstrated "presence." I asked if was compatible with Microsoft's presence, and he said it depended on whether MS is xmpp compatible. Is it? If not, what protocols does MS presence require?


I had a great time researching this (Bing to the rescue!) Actually the answer came quick: “No, our IM protocol is based on SIMPLE (Session Initiation Protocol for Instant Messaging and Presence Leveraging Extensions) not on XMPP.”

What took more time was “why”. Obviously there are lots of players in the XMPP space and really only IBM and Microsoft in the SIMPLE space. It appears that our choice of SIMPLE was because we adopted SIP as our voice communications standard and since the “S” of SIMPLE stands for SIP… you get the rest. The alternative was to support two protocols (I think Cisco has taken this approach) where we use SIP for voice and XMPP for IM and some gateway software to unify the solution; I’m guessing we avoided that because of the additional complexity of having to support two communications protocols.

This makes building a single device that is both a SIP phone and can display presence much easier – see the Polycom CX500, CX600, and CX700 devices.