When T-Mobile launched its Facebook-enhanced VoIP service, called Bobsled, earlier this year, it fell short of competitors like Skype and Google Talk by only offering internet-to-internet calls. Now, with today's announcement of free calls to landline and mobile phone numbers in the US, Canada, and Puerto Rico, Bobsled's catching up to its competitors while still offering the Facebook phone calls that made it unique.

Bobsled's Facebook functionality allows users to make internet-to-internet calls to friends via its desktop program or newly updated Android and iOS apps. The new outbound call feature, however, only works with the desktop app — for now, at least, T-Mobile won't cannibalize its profits by offering the free calls via the service's Android and iOS apps. If you're wondering why the iPhone-less carrier would offer an iOS app, it's because Bobsled is a separate entity from T-Mobile. As to whether the combination of voice calls to Facebook friends and (now) free calls to landlines will be enough to entice users away from services with larger installed bases, we'll just have to wait and see. Bobsled's new functionality will start working today with the desktop application, which is available as a free download.