T-Mobile announced today that its Bobsled VoIP service is now available on Android smartphones and tablets. Bobsled, developed by Vivox and previously available for desktop broswers only, allows you to call your Facebook contacts for free from your device. Instead of dialing a number, simply select your Facebook friend and Bobsled will call or send a voice message for you. T-Mobile has also updated the browser version with free calling to any mobile or landline device within the U.S. and Canada. Despite its name, Bobsled is available on all carriers, and can be downloaded from the Android Market after the break.