I think it's definitely possible with GSM technology, and it was one of the things that looked like a 'stretch' in the film.

The reason cellphones are banned on aeroplanes is more down to the fact that causes the networks a lot of problems because reception is too good. Once you are a few kms up, your phone becomes visible to a load of different basestations at once (clear line of sight to them), as opposed to maybe one or two when you're on the ground.

This gives you an excellent chance of making a call but can cause problems with the routing software that the mobile networks use to figure out which cell you're 'in' and whether or not you are moving from one cell to another. To the network it looks like you are in multiple cells at once and moving rapidly into other multiple cells. If planeloads of people were whizzing around up there, registered on your network, there would be plenty of problems.

And before someone says that the plane is a faraday cage acting to block reception, haven't you ever seen people switch on and use their phones in the plane on the ground after it has parked on the stand? They work perfectly. Once when my plane was delayed on the ground in Zuerich the pilot gave permission to use phones and everyone was calling with no problems.

Of course, the US uses a different standard for mobile phones but I'd be very surprised if it didn't work in a very similar way.


Gav