Microsoft has announced the names of leading IP private branch exchange (PBX) and gateway vendors who have promised to make their products interoperable with its forthcoming unified communications platform, Office Communications Server (OCS) 2007.

Those same vendors say Microsoft does not have the experience or the technology to completely replace the IP private branch exchange with desktop telephony. Rather, enterprise buyers will continue to demand the choice of advanced features, security and performance that their proprietary PBX solutions provide, or at least close integration between their existing PBX and OCS 2007, due this summer.

Partners pledging interoperability include Alcatel-Lucent, Avaya, Cisco Systems, Ericsson, Genesys Telecommunications Laboratories, Mitel Networks, NEC, Nortel Networks, Siemens Enterprise Communications, AudioCodes, Dialogic and Quintum Technologies.

Richard Jenner, Avaya EMEA product manager for unified communications, said Microsoft is not pushing itself as an IP PBX vendor yet, though it already has point-to-point IP telephony capabilities.

“Microsoft has a long way to go before it can become a voice vendor. It needs to offer quality of service, voice switching and security,” Jenner said. “Nobody in the enterprise market would take a Microsoft desktop telephony solution and use it as a replacement for a PBX – you need the infrastructure behind it. If you want to run them [OCS 2007 and the IP PBX] in a complementary fashion, the integration can be done.”

Microsoft denied OCS 207 was intended as a “rip and replace” for companies’ existing IP PBXs, however. The unified communications platform will only deliver a subset of basic IP telephony features that falls some way short of those on offer from Avaya, Cisco et al.

Even so, OCS 2007 can be used as a simplified alternative to complex and expensive IP PBXs, delivering a presence-aware desktop telephony solution that offers voice, IM and conferencing. It is based on a union of Microsoft’s Exchange messaging solution, Live Communications Server (LCS) and Office Communicator telephony client.

It will be backed up by a host of new telephony end-point devices announced earlier this month by vendors including NEC, Nortel and Samsung, designed specifically as an alternative to the expensive proprietary IP handsets on offer from IP PBX vendors.