I have to admit I never paid much attention to the April 2011 Bobsled service announcement since it looked like a way to just call Facebook friends and I thought it had limited functionality. T-Mobile just announced some major enhancements and advanced functionality so you can now call any mobile or landline number in the U.S., Canada, and Puerto Rico for free from the Bobsled application loaded on your PC or Mac browser.
T-Mobile also released apps for Android and iOS that let you call or send a voice message to your Facebook friends. These mobile apps are free and do not support the same service functionality as you can get through your computer. Bobsled is a VoIP service and should not be used as a full phone replacement, but could save you quite a bit of money if you have an iOS or Android device.