A:Answer One will only have GPS capability and will need to be near the iPhone to work, the Unlocked (meaning not tied to any one cell service carrier) or any other cell carrier option will require the purchase of an additional service plan but will work regardless of the location of the iPhone or if the iPhone is even turned on. It treats the watch not like a companion to the Phone, but a separate device altogether. No need to piggyback off of your iPhone’s cell service.