A:Answer By adding a cellular line to your watch you have the benefit of still being able to make and receive calls, messages etc., should you forget your cell phone or not have it with you. This would require of course adding a line to your cellphone acct, which for us was an extra $10 a month. I feel it’s worth it because we can take walks and runs without taking our cells. Plus should you forget your cell and don’t have time to make a return trip, you don’t have to worry, you have your watch. We just upgraded to the series 6. We previously had Series 1 and 2.