Microsoft Chairman Bill Gates Tuesday launched the company’s unified communication platform, a milestone he said validates the era of software-enabled voice technology and signals the impending death of the PBX.

Gates and Jeff Raikes, president of Microsoft’s business division, formally launched Office Communications Server (OCS) 2007 and Office Communicator 2007, the client side of Microsoft’s unified communication platform. The major upgrade over OCS’s predecessor, Live Communications Server (LCS) 2005, is the addition of sophisticated voice technology.

“What today’s announcement is about is taking the magic of software and applying it to phone calls,” Gates said. “Once you get software in the mix the capabilities go way beyond what anybody thinks of today when they think of phone calls. This is a complete transformation of the business of the PBX.”

OCS 2007 is the centerpiece of Microsoft’s unified communications strategy to bring together e-mail, instant messaging, presence, voice and video. It is a Session Initiation Protocol (SIP)-based server that can route and switch IP-based voice traffic, as well as IM and Web conferencing sessions. With Microsoft’s Office Communicator and other client technology as the front end to the server, Microsoft hopes to storm the voice market that is attracting heavyweights such as Cisco and IBM.

Click to see: Photo of Bill Gates and Jeff Raikes

Gates likened the PBX to the mainframe of years ago, an all-inclusive system that lacked flexibility. He said moving voice to software would bring efficiencies to workers and IT, and reduce infrastructure and operating costs.

Raikes added that the cost of VoIP and a complete unified communications platform would be 50% less in three years than what it is today.

But Gates acknowledged that the PBX won’t be out in the dumpster tomorrow morning. He said voice would move to software over a period of time and work alongside the PBX into the near future, but eventually the PBX would disappear.

Today’s reality is that presence and IM are the primary drivers of unified communication adoption and not voice. And the other reality is that these individual communication applications are not unified under a single, coherent platform, especially in terms of management.

Regardless, Raikes repeated during the keynote address a prediction he made in March that within three years more than 100 million people doing information work will be able to click to communicate.