I am an avionics engineer and some years ago I was called to a 737 classic cockpit where the captain explained that the mcp (auto pilot mode control panel on the glareshield) was going nuts with the heading select and both course select displays changing wildly with confirmation on both ehsi's. Neither the crew or I had ever seen anything like it and after discussion believed it had to be some sort of interferance. On departing the cockpit to check things out downstairs in the electronics compartment I bumped into a passenger who was answering his mobile phone and had moved into the front galley to finish the call (right above electronics compartment). When the phone was switched off - problem disappeared. The phone brand/info was collected by crew and sent off thru the company channels.
I know airbus aircraft consider their aircraft to be impervious to such interferance, probably due to better shielding for their fly by wire setup. But maybe the the restriction on use of phones is just generic due to the fact you dont know which type of aircraft you will necessarily be travelling on. Besides how important is a call that cant wait till your on the ground - wasnt that long ago that the mobile phones didn't exist.
