I don't use a cell phone. (I don't need one. And, I don't like/can't stand them...)
And, besides what jxself said... Cell phones are also listening devices[1] and can give you brain cancer[2].(Make sure to check link number 1. Because, even if you use Replicant on one of them, you most probably can still be listened to...)
--- 1. http://www.youtube.com/watch?v=0G1fNjK9SXg 2. http://www.infowars.com/cell-phones-cause-brain-cancer-scientists-warn/
