My Brother has the above, and we have spotty reception in our building with the 7100t. Can I try 7280 with the sim from TMO? I have no idea if they are locked or if there will be harmed if I try. Any help greatly appreciated!

Well you won't hurt the phone by trying, but I can almost guarantee you the ATT phone is locked. ATT always locked ALL their phones. It was easy to unlock my family's Sony Ericsson phones, but to get a BlackBerry unlocked you're looking at $100. Unless of course he's currently an ATT customer, in which case he can call up Cingular, tell them he'll be travelling overseas, and ask nicely to provide the unlock code. That may or may not work. I wouldn't count on it.

Thanks for the reply... what if he's already gone overseas and it worked while he was over there? Does that indicate that it has been unlocked?

No. Only if he put another SIM card in it and it worked does it mean that it's unlocked. My father used his locked ATT phone in Switzerland, with his ATT SIM in it, but it cost him a lot. You generally ask the carriers to provide an unlock code when going overseas so you can buy a prepaid SIM when you get there and it won't cost as much to make calls...kind of like using a prepaid phone card.

On the ATT 7280, I found a site in the uk called: http://www.m-99.co.uk/Mobile_Phone_Unlocking/ Blackberry/blackberry.html

they want $19.95 (EU). all they need is the IMEI number and will send you the unlocking code. you get the IMEI number by entering *#06#

has anyone found that this works?

Wow, I would be EXTREMELY skeptical about that working. Each BlackBerry has a unique unlock code, and so far BongoWireless is one of the only vendors I know of that can do it reliably and they charge $100. If you do decide to try it, please make sure you post the results here so other people know whether or not to try getting their BBs unlocked from them.

EDIT: OK, read the page more closely, DON'T do it. They state they can only unlock Vodaphone-supplied BlackBerries.