Ahead of the official release, Microsoft said it will make the technology available to 2,500 companies for testing.
The new voice server will allow users to instantly call anyone from within Office applications by clicking on a person's name and initiating a call.
For example, a worker who receives an e-mail in Office Outlook from various colleagues can simply click on each colleague's name to check their availability and place a person-to-person phone call or arrange a conference call.
The company's push into the business telephone market pits Microsoft against Cisco, IBM and other technology companies seeking to cash in on growing demand for VoIP.
Microsoft Chief Executive Steve Ballmer has predicted that within 10 years all business communications will be Web-based, meaning hundreds of millions of people will change how they communicate.