A:AnswerYou have to have the cellular version to be able to connect a cellular data plan to the watch. You will receive messages and calls on the gps model only if your cell phone is connected via Bluetooth and is in close range to your cell phone.
A:AnswerGPS only works with wifi or your phone via Bluetooth. Unlocked you have to purchase a separate SIM card and connect with a wireless provider such as att or Verizon etc
A:AnswerYou push the button on the back of the watch and slide the band out. Do that for both sides. Slide the new band in until you hear it click in place