I'll take it one step further. FAA rules REQUIRE cell phones to be turned off BEFORE a commercial jet reaches the runway for take off and left off till after the plane has cleared the runway after landing. This is due to known RF interference with aircraft navigation systems. I've seen a VOR receiver go nuts because a cell phone was being used just outside the electronics bay during a maintenance cycle. Considering that the VOR system is one of the primary navigation systems used on commercial AND PRIVATE aircraft, I have no doubt that cell phones can and will affect a modern computer radio's ability to control an R/C aircraft. Having a cell phone on the flightline, in my opinion, should be banned by all flying clubs to prevent an accident from getting someone hurt, or worse.