Burning Question: Why Can't I Use My Cell Phone on a Plane?: "Part of it, naturally, comes from the call carriers. When phones ping for signals at 35,000 feet, they can hit hundreds of towers at once, necessitating complicated parsing of roaming agreements. Providers don't want the hassle if they're not being properly compensated, so the government has left the plane ban in place."
from when i worked in telecoms I knew that each time you change location you re register with a HLR system. being in a fast moving object means that you re register too frequently for the networks to cope. I hadnt considered you'd be detected by multiple HLRs.
It did seem that the usual excuse that they interfer with the avionics was a load of tosh else all bin larden and his affliates would have to do is board planes and turn thier phones on and they'd drop out of the sky. if that were true we would be depositing our phones with our liquids in the bin