The average cost of a VoIP service for business will fall by 50 per cent in three years, a senior Microsoft executive predicted today.

Jeff Raikes, president of Microsoft's Business Division, said that prices will plummet as VoIP systems move from hardware to software.

He also predicted that 100 million people, twice the number of current business VoIP users, will have the ability to make phone calls from Microsoft Office applications in the same time frame.

"Software is set to transform business phone systems as profoundly as it has transformed virtually every other form of workplace communication," said Raikes.

"Over time, the software-based VoIP technology built into Microsoft Office Communications Server and Microsoft Office Communicator will offer so much value and cost savings that it will make the standard telephone look like that old typewriter that's gathering dust in the stockroom."

Raikes claimed that standard telephone calls are very inefficient compared to VoIP. He pointed to a Harris Interactive survey which found that two-thirds of business phone calls end in voice-mail messages.

As a result, 25 per cent of information workers spend the equivalent of three working days each year playing phone tag and leaving voice-mail messages.

Raikes said that Microsoft will distribute the public beta version of Office Communications Server 2007, Microsoft's VoIP and unified communications server, and Office Communicator 2007, Microsoft's unified communications client, to testers later this month.