Today, we announced a partnership with MCI to enable VOIP technologies that make it possible to make phone calls from Internet-conneced Windows PCs to POTS-connected Telephones.
I firmly believe that the next evolution of this will be the complete enablement of phone calls through mobile devices over Bluetooth through Instant Messaging systems. Imagine picking up a Bluetooth-enabled mobile device that has a dial pad on it that allows you to dial a phone number and make a phone call through your PC wirelessly. This provides the "phone experience" that is currently missing from the PC-to-Phone platform.
Kurt Shintaku's Blog 