Correct ... AT&T Wireless was and Cingular is GSM, while Alltel is CDMA.
Alltel does own some GSM coverage in the West and Southeast as the result of acquisitions, but Alltel does not sell GSM service to its customers; the GSM in former Western Wireless territory in the West only serves roamers from other carriers, and the GSM in former PSC Wireless territory in the Southeast only serves a small number of acquired customers (until they are weaned off GSM to CDMA anyway) and roamers.
This statement is partly incorrect. Cingular IS requiring that new customers accept Cingular-branded equipment when activating service (and AIUI, T-Mobile USA is too, but unlike Cingular only for activations through indirect sales channels), but Cingular, like every other GSM carrier in the world, does NOT prevent GSM customers from using their own equipment. Technically, Cingular could do so via a variant of IMEI blacklisting, but no US carrier uses IMEI blacklisting at all and no carrier in the world does it except for phones reported lost or stolen.
The problem in this case is almost certainly that the Treo is locked to the AT&T network (programmed to only accept an 'AT&T SIM') and won't accept a 'Cingular SIM' ...but that can be very easily worked around via any number of third-party unlocking services. Cingular itself won't provide unlock codes for AT&T-branded equipment because a) AT&T Wireless flatly refused to provide unlock codes under any circumstances for equipment it sold (AFAIK, they were one of the only GSM carriers in the world, if not *the* only one, with such a harsh and restrictive policy) and b) Cingular wants all AT&T-branded equipment out of customers' hands so it can put Cingular-branded equipment in their hands. (Cingular DOES provide unlock codes for Cingular-branded equipment when certain conditions involving length of service, account status, are met.)
The solution in this specific instance is to:
- get the Treo unlocked via a third-party unlocking service (this would involve taking or shipping the Treo somewhere; AFAIK, there are no "remote unlock" options available for Treos like there are for virtually all Nokias and some Motorolas);
- activate a new line of service with Cingular with no data plan, accepting any old phone (preferably one that is free or very cheap with a contract);
- move the SIM from the free/cheap phone to the Treo;
- request the PDA data plan on the newly activated line.
Cingular generally doesn't allow *TDMA* users (what few there are left) to do so, but as stated above, they can't exert the same power over *GSM* users -- well, technically they could, but they don't.
That is utter cow manure ... IF THE TREO WERE UNLOCKED, which Cingular itself could do by providing unlock codes but simply refuses to do for "AT&T"-branded equipment because of "marketing" policies, it would work on Cingular's network -- or on the network of any other GSM carrier in the world -- just fine. All Treo firmware, including carrier-specific versions, already contains all settings needed to run on the networks of Cingular and a wide variety of other GSM carriers in the US and around the world, and even if it didn't, GSM is standardized enough that getting any device up and running fully on any network just entails changing a few settings to get data and SMS/MMS working, and to get basic voice service working even that isn't necessary.
FWIW, I have a Treo 650 running on T-Mobile USA despite their not selling or officially supporting it. I bought an unlocked 650 directly from Palm(One) and just moved my SIM over from my previous device, a T-Mobile Sidekick, after activating a data plan appropriate for the Treo; as soon as I put my SIM in the Treo it configured itself with the data and SMS/MMS settings required by T-Mobile's network and has worked flawlessly with my T-Mobile service ever since.
Stanley Cline // Telco Boi // sc1 at roamer1 dot org //
"it seems like all you ever buy is Abercrombie and cell phones" --a friend