It's just what Cingular said, the phone does GSM, TDMA, and AMPS. The SIM is just for GSM, so for TDMA and AMPS they need to know the ESN of the phone. I didn't realize that they'd turn on TDMA service on a GSM account. I'll call them tomorrow and see if they'll enable my wife's phone for TDMA as well.
John[TELECOM Digest Editor's Note: The Cingular lady would not commit to it either way, except to say to me that 'in rural areas, still in transition' they more or less had to do it or wind up writing off a lot of their customer base. I know that when I first got the Nokia 6010, because of my geographic location (southeast side of town and relatively close to a GSM tower [but not _all_ that close] I was able to use GSM with no hassles. But, the first time I got in the taxicab and had Jeff (our taxi driver here in town) take me out to the 'west side' (west Main Street, sort of around Austins, our notorious 'hard acid rock', semi-gay bar) the phone quit working on GSM and instead told me it could not find a tower. When I took the 6310-i in that same direction (but before reporting my ESN, IME and 'serial number' to Cingular) the phone did 'seamlessly slide over' to the proper band to use and instead of getting no signal at all, I got the jingle and 'we do not recognize your number' message. When I got back home, the phone tried 'seamlessly' swapping back and forth and I sometimes got out, but when the GSM tower was booked up, I would get that jingle tone as the phone tried work on the nearest TDMA tower it could find. Before I knew this, I was ready to throw in the towel and send the new 'gate' phone back in the mail. When the Cingular lady told me 'even with a GSM phone and a SIM card, it is a good idea to call us anyway and turn in your ESN in order to get _full coverage_ with your phone, then I understood what she meant. Before, I just thought she was being nosy by telling me I should always call to report the ESN. PAT]