Everyone here hates the T-Mobile phones but I think that's because T-Mobile has such poor coverage in the US. I've not seen any Cingular Blackberries here so I can't compare the audio quality (whether it is a coverage issue or a 7230 issue)
(Cingular and T-Mobile are the only GSM services in the US) Cingular serves about 50 million customers, T-Mobile probably has about 10 million.
Prior: BES: 7510, 7520, 7290, 7230, 7130, 8220 (No Data Plan), Droid Eris
Post your question on the forum, don't PM me.