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Federated presence is a hot topic at the moment, as the vendors argue over how interoperability will work.
Microsoft's concept of federation revolves around identity management and its Active Directory authentication tools, but it doesn't work both ways. While a Cisco system will share the presence status of its users with a Microsoft system, Microsoft doesn't reciprocate by sharing the presence status of its users with the Cisco system.
As a relative latecomer to the communications field compared to dominant players such as Cisco, Microsoft is starting from behind and favours limited interoperability in order to help it catch up, says Forrester Research senior analyst Tim Sheedy.
"If you look all the way back to what Microsoft did with their consumer instant messenger application, they certainly were open in their approach in terms of trying to be interoperable. The major reason for that was they were coming from behind so they were the ones that were going to benefit," Sheedy says.
When Microsoft's fledging MSN Messenger application was competing against the dominance of AOL's AIM in the late 1990s, Microsoft made MSN Messenger interoperable with AIM. AOL responded by blocking MSN users, which Microsoft circumnavigated, and the two services played a cat and mouse game for several years before Microsoft conceded.
Once MSN Messenger established itself in the instant messaging space, a process boosted by the bundling of the software with Windows XP, Microsoft's passion for instant messaging interoperability waned until the recent deal with Yahoo! Messenger in light a growing competition from the likes of Google and Skype.
Today Microsoft is fighting to break the grip Cisco, Avaya and others have on "the stack" of communications applications within an organisation, by using interoperability to establish a foothold.
"The technology today is mature enough that an organisation can integrate systems, so they don't have to buy a vertically integrated stack all from one vendor, which historically they had to do," says Microsoft's Trimboli.
"The industry is at this tipping point where it's moving from vertical stacks to horizontally integrated applications and processes."
Next: The future of presence