I agree with 2slow... I don't have a cell phone and don't want one. Not because I'm worried about interference, but because when I'm at the field I leave the real world behind and relax with my friends and my planes.

In all seriousness though, there are a lot of them at my field and I have never heard of a problem. Nice to be able to call for help whenever you might need it. Or order a pizza![8D]