4/29/2008 -- Who's on top in the red-hot unified communications (UC) segment? That depends on how you define "top."

According to market watcher Infonetics Research, both Cisco Systems Inc. and Microsoft Corp. are tops, overall, in the UC space, with Avaya and Nortel also coming on strong. In fact, buyers say that Cisco and Microsoft are their preferred Unified Messaging and Communicator suppliers.

But the struggle is just beginning, Infonetics said, and no single vendor has an ineradicable purchase on UC market leadership.

More to the point, Infonetics said, UC leadership could hinge on which vendor's vision of next-gen unified communications ultimately wins out.

"It's no secret that Microsoft is predicting the death of the PBX, to be replaced by a software-based communication approach like OCS 2007, but we didn't find many people convinced that this is yet the way to go," said Matthias Machowinski, directing analyst for enterprise voice and data at Infonetics, in a statement. "What we're seeing instead is companies keeping their IP PBXs, and layering unified communications applications on top."

Microsoft isn't putting all of its eggs in one basket, of course. "Microsoft is seeing early success by leveraging their leadership in e-mail messaging and desktop environments," Machowinski said. "The incumbent IP telephony players are also faring well," he continued, stressing that the competitive outlook in the still-gestating UC landscape remains fluid.

"There are still opportunities ahead for vendors looking to get into or ahead in the unified communications market, because many buyers don't yet know who they will be buying from two years from now," Machowinski said.

Infonetics recently asked survey respondents to rate a quintet of UC vendors -- Avaya, Cisco, IBM, Microsoft and Nortel -- on a range of issues, including reliability, value, innovation, pricing and features. No single vendor came out on top, according to Infonetics; while Cisco's solution earned high marks for reliability and low marks for pricing, Microsoft's received poor ratings for reliability and high ratings for financial stability. And no one fared well on the interoperability front. --Stephen Swoyer