Google Testing Google Voice Desktop App Internally
Last November Google acquired Gizmo5, a VoIP service that competed with Skype by making P2P VoIP calls as well as making and receiving calls with POTS (normal landlines) and mobile phones.
Gizmo5 fills some of the holes in the Google Voice product, particularly providing an endpoint for calls. Currently Google Voice users must assign their Google Voice phone number to an actual phone to make and receive calls.
Read more: techcrunch.com