Microsoft and nine hardware partners will unveil 15 IP phone devices at the Windows Hardware Engineering Conference in Los Angeles today. 

The announcement forms part of Microsoft's broader unified communications strategy.

Jeff Raikes, business division president at Microsoft, said in March that 100 million people - twice the number of current business VoIP users - will have the ability to make calls from Microsoft Office applications within the next three years.  

Microsoft's unified communications strategy aims to integrate fixed-line and mobile voice, instant messaging, email, web conferencing, video calls and presence information based on Office Communications Server (OCS) 2007, currently in beta.

The 15 devices to be shown today include hybrid phones which can connect to OCS 2007, and use a conventional PBX voice network, PC-dependent handsets and headsets and fully integrated systems.

For example, Samsung has built a monitor with camera, speakers and microphone which can be used as a conventional PC desktop screen and a calling device.

Bluetooth headset maker Jabra is offering a hands-free earpiece, while Asus is showing off an OCS-compatible laptop equipped with camera, speaker and microphone. 

Other partners include Vitalix, Polycom, Plantronics, Tatung, NEC and a joint venture between LG and Nortel. 

Microsoft's unified communications strategy will free users from the tyranny of single-vendor lock-in which is prevalent in conventional telecoms, according to Mark Deakin, unified communications product manager at Microsoft.

"Users should be free to use any device," he said.