Sigh. Not this again.
Airplanes don't fall out of the sky because, first, there's a pilot on board to think about what his instruments are telling him. Second, airplanes usually have back-up systems for important stuff.
NASA has a voluntary database of in-flight incidents. There are issues related to "Passenger Electronic Devices" (Event Type category is "Flight Deck/Cabin/Aircraft Event" and value is "Passenger Electronic Device") that don't cause the plane to crash. However, it can affect aircraft radios used for navigation and voice communication and, on rare occasions, will cause the autopilot to disengage--assumedly due to odd signals being received from the above.
So the whole, "I don't know of any planes that have crashed because of a cellphone call" doesn't mean there isn't interference. It just means that the pilots handle it--sometimes by having the Flight Attendants re-check to make sure that people have turned things off. I remember reading about a pilot who got a signal that one of the cargo doors had opened while at 30,000 feet. He ignored it because if that signal had been true, he'd also see a whole bunch of other warnings about depressurization and the plane would probably be acting strangely.
Recently a Maysian Airlines flight went missing. You may have heard about it in the news. Nobody can understand why the pilots would have deviated from their course and had trouble communicating...