Sony Ericsson T637

From what I've been hearing, if you don't mind staying with At&t till the end of you contract with them, then you won't need to worry about getting a new phone. You will be able to keep it as long as you don't migrate to Cingular. But if your contract is at least a year or two left on it, that shouldn't really matter, because by then you will probably want a new phone by then. So I hope that answers you question.

The 64k SIM is no different in size or function than the 32k SIM, even if the t637 doesn't have the ENS programming then it will still work. So go ahead and grab it. However I'd suggest getting it with Cingular instead of AT&T, wait a few more days and they'll have new promotions as well as a combined coverage map for you to see. The new t637 that you'll get will most likely have a 64k SIM and you won't have to worry about whether to migrate or not cause you'll already be on Cingular.

IN terms of migrating to Cingular, make sure you are in a market where Cingular has the new serivce if you are in a divested market (Carolina's) you will not be able to migrate you will have to port over and standard etf's if applicable wil be assessed. The new 64K sim card will not work completely in the ATT phone, it will not support all of the Cingular features such as mms, txt and data browsing, as well Cingular will not be able to privide you with Insurance or wex options, or even basic troubleshooting. The answer you will get if you have any problems or concerns with connection, coverage or equipment problems, will be that because it is a different carrier they cannot help you.