Although it is possible to make calls from aircraft...the physical nature of a cellular network makes consistant success in calling unlikely.
The network is designed to pass a mobile user from one cell to the next....once the aircraft is at altitude the computer that passes off calls will become confused because it is not expecting a call from overhead...the signal strength will appear to be equal at several "receiving" cell towers....hence the likelyhood of dropped calls is raised significantly.
In landings and takeoffs (lower altitudes) I see no problems.
I worked for a major cellular provider for a number of years.
No, the real reason was that it tied up a port in multiple cells. Maybe *your* company the confusion problem.
That, and airlines could make money off the phones in the planes.
I'm guessing the cell companies have tweaked the software to handle "at altitude" planes without
the resource waste, and they hired Mrs. Daschle or the like to lobby the FAA...
Finally, someone who truly understands why they were banned in the first place. The cell co. requested this because the software could not handle more the 3(I think that was the number) towers picking up a single phone.