[OT] Mobile phones - why they aren't all avaiable on all networks?

["Pedro de Oliveira" <groups@xxxxxxxxxxxxxx>]

All

I'm on T-mobile and have been for all of my mobile life, contract after
contract, upgrading phones as the contracts end.  Two months ago my
contract ended and instead of upgrading at the time I decided to wait
until the Nokia 6600 was launched.  It's now been launched but t-mobile
won't be selling any which means I either have to get another handset or
get another network.  Does anyone know why aren't all phones available
to all networks?  Is there some scientific reason??

Cheers
Pedro