A warning, if you are trying to by a nokia 6260 to use on cingular, it will not work, because cingular is switching its frequency to 850Mhz. Nokia 6260 is triband and will only work on 900 1800 1900 Mhz's.
I just got mine recently and during cingulars change i noticed my phone was not receiving any singals. It took a lot of back and forth phone calls btw me and cingulars customer service, and some research to realize this change.
I'm stock with my contract with cingular because it would cost me more to leave than to get a new phone.
For now, the 6260 should work with T-Mobile. They are based on a 1900Mhz frequency.
Not quite true. Cingular uses both 850 and 1900 MHz, but some markets use one or the other exclusively. Some markets use both. If you live in an 850-only market area, then this phone would not work. However, in areas like Phoenix, Chicago, and others, which use 1900-only, this phone will work as well as any other.
Yes, but my point was that Cingular is not "switching" frequencies. Even the version with 900/1800/1900 will work just fine in markets where Cingular (or, previously, AT&T WirelesS) uses 1900 MHz. Their network in those markets is a 1900 network, just as T-Mobile's is. In some other markets, Cingular uses both bands, and in a few others, is 850-only.