A:Answer The GPS means that it does not have cellular service. If you purchase the GPS version it works off wifi and bluetooth connection to your phone. If you purchase the cellular version, then yea you would need to get cellular service and if you have Sprint, I would buy a Cellular Apple Watch that is for Sprint. The cellular version allows you to use watch and leave your phone at home and make and receive all communication that you would normally get with your cell phone. Whereas the GPS version needs to be in range of your cell phone to make and receive calls, emails, and other notifications.