MCI and Microsoft are teaming up to provide a VoIP phone service that lets customers make phone calls from their PCs to traditional phones that are connected to the public phone network.

Called MCI Web Calling for Windows Live Call, the service is currently in beta testing, but will be generally launched next year, the companies say. Final pricing is not available, but during testing, calls cost 2.3 cents per minute.

The service allows customers with the upcoming Microsoft Windows Live Messenger software on their computers to make calls by clicking on entries in their Live Messenger contact list. MCI routers divert the calls from the MCI IP network to the public phone network. Live Call replaces MSN Messenger.

Customers can place calls but can't receive them. So there is no way for a person who receives a voice mail from a person calling via the service to return the call to the PC. They'd have to call them on some other phone or contact them via PC-to-PC, a feature already supported by MSN Messenger.

Instructions on how to sign up for the service will come with Live Call, and customers will buy prepaid minutes in $5, $10 or $25 increments.

Initially the service is available only in the U.S., but the companies have plans to expand it soon to France, Germany, Spain and the U.K.