try the textfree or pinger app. Nice voice quality and SMS, and multiple numbers and locations can be had. There are ads on the free version, I just pay the 5$ for the paid version to get rid of them, especially when travelling abroad so ad loading doesn't suck up any precious data bandwidth. App is very very reliable. Minutes are not FREE, although you can do things like tweet it, or download other apps to get a bunch of free ones, or buy them for like 1cent for 10 minutes time.