Be extremely careful when using a non iPhone AT&T sim in an iPhone. If you forget and start using some of the widgets or Safari, it will eat up all your time in literally minutes. Just turn off edge completely on the iPhone so there won't be any mistakes.
I accidentally wiped out $25 in about 20 minutes while listening to Flytunes one night. I had it set on WiFi but when the iPhone automatically turns off the display, it changes to edge and there goes all the funds in the account.
Anyways, I can't use my non iPhone AT&T in my 1.1.2 iPhone even after Ziphone and unlocking. I can use it on one of my 1.1.3 iPhones after Ziphone and unlocking.
Interestingly enough, a third iPhone I have using a iPhone GoPhone plan, has it's sim tied to that iPhone exclusively. This phone started out at 1.1.2 OTB and I upgraded to 1.1.3. If I try to use that sim in my 1.1.2 iPhone mentioned above, it won't work even after Ziphone unlock. If I take that sim and put it in my 1.1.3 iPhone that is UNLOCKED, the sim will work. Also, If I downgrade the GoPhone iPhone back to 1.1.2, this sim card won't activate the iPhone till I upgrade back to 1.1.3.
Now another weird thing: On my other 1.1.3 iPhone which is a 16GB iPhone, using my original sim from July 6, that sim will work in any of my other two iPhones regardless of firmware version even if locked.
This whole thing with these sims is really confusing. AT&T and Apple are really trying to lock sim cards to one phone with 1.1.3.