Not unless you buy the gps plus LTE version of the watch. Even then, you can choose not to have a cellular data plan connected to your watch. ($40 activation plus $10/mo depending on carrier ( I have Verizon, so am only familiar with their rates.). If you have the gps only version of the watch, you cannot receive calls unless your watch and phone are in range of each If they are within the range parameters, you can receive but cannot make calls from your watch. If you have the gps plus LTE version of the watch, you can leave your phone at home and use the watch as an independent device to both make and receive calls no matter if your phone is within range of your watch or not; for this service, your watch would need to be connected to whatever carrier you use for your iphone. Also, be sure your phone is an IPhone 6 or newer in order to be comparable with your watch if the watch is generation 4 or 5 (watches of generation 3 or older need an Iphone 5 or newer.) Hope this helps—and enjoy your new Apple Watch!