A:AnswerYou're celluar provider would be able to answer this question best if you're speaking of the 3g version. If you're just speaking of the regular bluetooh vs it should work anywhere as long as your phone is nearby.
A:AnswerYes, you can. In fact, that's exactly what I am doing. I have a Sprint Samsung Galaxy S6 Edge paired up with a white Gear S2 3G from AT&T. I use the watch through the Bluetooth connection. Everything that works on the S2 Sport and S2 Classic also work on the S2 3G.
A:AnswerYou can purchase the watch without being on AT&T but it won't be a standalone. You would only be able to connect it via Bluetooth but it won't be the $99.99 price unless you activate it on a two year contract.
A:AnswerYes, the 3G models have a speaker. The basic model does not. You can take calls through the basic one, but your phone will turn on and you'll be using your phone's hands free loudspeaker. All of the watches have a microphone. But not all have speakers.
