Microsoft has released Office Communications Server 2007 to about 2,500 IT professionals in the US in a private beta, said Paul Duffy, a group product manager at Microsoft.

It's the first time Microsoft has offered software for making voice over Internet Protocol (VoIP) part of an integrated communications service, with corporate instant messaging, email and video conferencing all running on one IP network, he said.

Office Communications Server 2007 runs in conjunction with Office Communicator 2007, which is the accompanying desktop software.

In July, Microsoft announced a strategic alliance with Nortel calling for interoperability between Microsoft communications software and networking infrastructure from Nortel. Office Communications Server 2007 also will interoperate with products from Avaya, NEC Phillips and Siemens Communications through the partnerships Microsoft has with those vendors.

"Customers can deploy Office Communications Server and Communicator with infrastructure they have - with IP telephony that they might have from one of those vendors - or they can deploy it in conjunction with an IP PSTN (public switched telephone network) gateway," said Duffy.

Though Microsoft is working with vendors on VoIP, there is some belief in the industry that the company eventually will look to provide the entire software infrastructure for VoIP and other communications offerings. Such a move would hardly be a stretch, as Microsoft's strategy for entering new markets has often been to partner with companies that specialise in certain software until it is able to build out its own portfolio.

Office Communications Server and Office Communicator 2007 are expected to be available in the second quarter of 2007.