Obviously you are not giving the whole story. No carrier can refuse to port your mobile phone # to another carrier. If you cancelled your original account with Cingular first then there would be a problem. All you do is simply go to the new carrier first to request the change and it is transferred. You do not need to contact the old provider in any way. While some delays occur, no carrier can refuse to port out a number.
Please give more details about the problem that occurred.
Please be advised, if you are considering changing carriers and wish to keep you phone number, you must sign on with a new carrier and transfer your number before you tell Cingular to cancel your account.
Once you tell Cingular to close your account, they lock your number and it cannot be moved. Period.
Maybe everone knows this but me, I was surely not informed of this by Cingular in the process.
No big deal, but don't be surprised.
Save yourself the hassle and plan ahead, and be advised.
I've been with ATT / Cingular for years, BTW. Thanks a bunch Cingular...
Happily a T-Moble customer now. Plus I feel better for telling someone...