Verizon is CDMA. A SIM lock can be removed, so you can change carriers. Verizon doesn't specifically do that--there is no "SIM lock" on a CDMA phone since there is no SIM--but will only accept a phone that was made for them. I've tried three times to get them to activate a generic CDMA phone, they said no.

Yup. Plus a TDMA phone would be incompatible anyway, but they won't activate a foreign CDMA phone or data card.

Depends on where you go in Mexico... Cozumel was still AMPS only when I was there 2-3 years ago. I was proud of my shiny 8890 world phone, which never got a signal, while my Wife's junky old TDMA/AMPS phone worked like a champ. Oh well.

Thanks for all the comments Carlos... you seem to know a lot about cellular. Did you get a chance to read my other post about Verizon? I only know a few things about cellular from a customer point-of-view and want to make sure I understand the limitations correctly. If there's absolutely no way to switch to Verizon and get iSync going, I guess I'll stay with Cingular and just look for a good deal on a used Sony.

Messages crossed, I posted on the Verizon question. They've told me no, and I've asked three times. I'd love to be proven wrong. Verizon has a very strong control attitude, and their crippling of BT phones shows just how anti-customer they are.

If they don't have an iSync compatible phone in their lineup, then I think you should stay with Cingular. Or look at T-Mobile; they generally have better coverage than Cingular, cost less, and have JD Powers' number 1 rating for customer service (Verizon fell just behind them this year).

Yeah, I saw that the posts crossed. Thanks for taking the time to post all that
.. sorry I kept getting TDMA/CDMA confused but now I know. I would have no problem going with T-mobile -- except I don't think it would help me. With Cingular my phone goes between 0 and 1 bar of signal when I'm at home... enough to ring the phone sometimes, but not enough to carry on conversation unless I walk out to the road. If there were a T-mobile tower near enough to work at home, wouldn't my phone roam over onto it when Cingular's signal drops down? Any way to check and see from the phone? If T-mobile were strong in my area, wouldn't I see my phone roam over onto them when Cingular drops out occasionally? I've never seen it do that...

Cingular's customer service people are really, really stupid. I've called the national 1-800 number multiple times, and visited both big Cingular company stores in my town (as well as a half-dozen of those fly-by-night phone stores), and between all of them I still haven't found anyone who knows how to help me set GPRS up on my 6230. Oh well, I guess I don't really need it.

Thanks again Carlos...

No, there may not be a roaming agreement between T-Mobile and Cingular in your area. Also, the phones have a very strong preference for the home carrier, so *any* signal may be enough to keep it from roaming.

You can see if there is T-Mobile coverage, but won't be able to check signal level unless you know how to get to the engineering menu in your handset. To see general coverage go into the networks menu, select the manual network selection option, and it will show all visible networks.

Customer service...Cingular was too small to be rated, but AT&T, which Cingular bought out, has a "D" rating by JD Power.

T-Mobile has a 15 day return policy on phones if they don't cover you where need them to.

Nokia, Sony phones with iSync
 

I"m on ATT Wireless/Cingular as well. I just swapped my Nokia 6620 phone for an unlocked Sony K700i. I was getting tired of the bare minimum Mac support that the Nokia had. With the 6620 I could transfer files and vCards to the phone via Bluetooth, but could not use iSync. The Sony K700i showed up in iSync right away, and has worked well since then. It's only been one day but so far I'm very happy with the switch.