Microsoft is expected to announce some changes to its Windows Messenger applications, including one that enables users of the forthcoming Windows XP operating system to make phone calls from a PC to a telephone.

Web-based phone services provider Dialpad Communications will announce today, in conjunction with Microsoft, that it is one of several IP (internet protocol) telephony companies offering its services from within the new Windows operating system.

The company has built an application with an interface that resembles a phone dialpad and allows users to make calls over the internet using voice over IP technology.

"It will give users the ability to do voice over IP with Windows XP and Windows Messenger," said Martina Ehlers, senior director and general manager of premium products for Dialpad.

The availability of Dialpad's internet phone service is part of a broader announcement Microsoft is making later today regarding its Windows Messenger application, a Microsoft spokesperson confirmed.

When Windows XP becomes widely available on 25 October, the software maker is also planning to launch an upgrade to its Windows Messenger client, which combines text, voice, and video chat in one application.