There's been little or no proof that cell phones will actually cause problems, especially the modern low-power spread spectrum, not old 3watt analogs. Most of the restrictions are A) precautionary and B) related to practical cell system confusion that results from a 2D system trying to deal with a 3D point.

The reason that electronics are not allowed during the first and last 10 minutes is that if there were a bizarre interaction, you might not have time to catch it and resolve it. At other times, the pilots could tell everyone to turn everything off to debug a minor navigation or radio problem.

Most electronics and even cell phones don't put out enough power in frequencies that are going to cause any problems. There is even talk about putting cells on planes to allow cell calls, relayed via satellite. Google: "cell service on commercial airlines".

The only reasonably possible way to interfere would be to tune an aircraft band radio to the tower frequency and block communications, but is an indirect risk.

sdw