Rumblings of a Facebook VoIP platform have been bouncing around for a while, and today it was revealed that such a platform is indeed coming -- with T-Mobile's help. According to a T-Mobile blog post, T-Mobile will be launching a free VoIP calling platform for Facebook users called Bobsled. Bobsled will be a brand T-Mobile says is "aimed at bridging the world of traditional telecommunications with Internet-based voice and data services."

The Facebook VoIP app specifically will be powered by Vivox, who has been offering embedded voice chat within Facebook games for several years.

Available for download here, the service allows Facebook's 500 million customers to engage in voice chat, or leave public or private voice messages on a user's wall. After installation, the application adds a small phone icon next to a friend's name, allowing one click voice communications.

According to T-Mobile, the next step is to integrate video chat, as well as the ability to place VoIP calls to mobile and landline U.S. numbers. T-Mobile also says they'll eventually offer applications on smartphones and tablets across various mobile platforms, "regardless of the carrier that powers such devices."