What does it mean when Carrier's phone list doesn't have a phone?
When I go to the carrier's page on Phone Scoop they list a number of phones but not always the one I want to use (usually the latest/greatest thing out). Does this mean that phone won't work on their network?
Not necessarily. GSM phones will work on GSM networks as long as the correct frequencies are there. For AT&T and T-Mobile, the phone needs to have GSM 1900. For Cingular, it needs to have both GSM 800 (850) and 1900.
Or just that the carrier doesn't offer the phone for sale in one of its own promotions? Or just that it hasn't been somehow 'certified'?
Correct on both.