In short Bobsled Calling is the most flexible voice service you’ll ever use. Make high quality calls to your Facebook friends and any number in the U.S., Canada or Puerto Rico from anywhere you have an Internet connection – even when you don’t have your phone!
Get is here: Browser, Android, iOS
Here is an more detailed article from Gizmodo:
Remember when T-Mobile launched Bobsled back in April, which enabled free VoIP calls between Facebook users? I didn’t either, but now that it’s added mobile apps, browser apps, and the capability to call regular phone numbers, it’s way more memorable.
This is a pretty major upgrade to a pretty slick service. Users have already been able to make free VoIP (that’s Voice over Internet Protocol) calls to each other from within Facebook, but it’s now breaking out of the social networking platform and onto others. The browser app (which will work for OSX and Windows in virtually any browser) allows you to call any phone number in the U.S., Canada, and Puerto Rico, for free. The kicker here is that you don’t have to be within one of those countries to use it, so if you have family in Albania, they can use this web service to call you on your home phone in Alabama and it won’t cost a thing. Um, that’s awesome. You can make calls from from the web without even downloading the app, but you’ll get better voice quality if you do. There is also text messaging built into the web app.
The mobile apps are going to be a welcome addition, too. As of today you can download the Bobsled app for iOS—even though T-Mobile doesn’t officially carry the iPhone!—or Android. They aren’t yet as fully capable as the browser apps in that they cannot dial out to regular phone numbers, but I was told that capability will be coming by the end of the year. In the meantime, you can make and receive Bobsled calls on any of your iOS or Android devices. When someone calls you, all of your devices that have the app will ring at once. You answer on the one you want, then the rest of them will be automatically silenced.
You can also call someone on Facebook who doesn’t yet have the Bobsled app installed. They will receive a Facebook notification that you’re trying to call them, and if they want to talk to you they’ll be prompted to grant Bobsled some permissions, and they can then call you back. If they don’t answer you can leave them a voicemail, which will appear on their wall or in their private messages, at your discretion (note: when calling from the mobile app you can only leave messages on their walls, currently). You can also go directly to leaving a voicemail without having to call. Integrating with Facebook was a smart move on T-Mobile’s part, since Facebook has such a colossal user-base already—it gives the service instant usability. Users without Facebook accounts, however, can simply sign up for an account on Bobsled.
I gotta say, this is a very interesting move from a wireless carrier. You’d think that they’d be trying to steer people away from VoIP, not toward it. It may end up being a genius, future-proofing play, though. VoIP and messaging over data (rather than SMS) is a rapidly growing market. There are currently no ads within Bobsled, but that’s definitely something they’ll be considering down the road, and they could charge for calling out to other countries, too. In addition to calling any number from mobile phones (which will be a big move), by the end of the year they also plan on offering unique phone numbers to users (similar to Google Voice). People would likely then have the option of transferring that number to a T-Mobile plan (or another service provider) if they wanted.
While this bears a lot in common to existing services like Google Voice and Skype, they are doing a fair amount to differentiate it. Now it’s just up to their marketing department to get it to catch on. The apps are all downloadable now. If you end up taking Bobsled for a spin, let us know what you think. [Browser, Android, iOS]
Source: http://gizmodo.com/5848466/t+mobiles-voip-bobsled-just-got-an-olympic+sized-upgrade