It is from AT&T. It's been on its contract with AT&T for a while, but it is hopefully going to be up soon with Verizon Wireless and possibly other carriers.
You don't "have" AT&T, the iPhone comes with the ability to connect to AT&T.
No, T-mobile does not have the iPhone. AT&T has it though.
T-Mobile does not have the Iphone only At&t does
There will not be an iPhone 4S for T-Mobile but you can get any iphone unlocked at unlockatt.com
Since the release of the iPhone, AT&T has had an exclusive contract with them. (Yes.)
No it is not. It is for AT&T unless you "jailbreak" and "unlock" an iphone. Instructions to do this can be found on the internet.
Yes, AT&T sells the iPhone in the store. You do not have to go to Apple to purchase one.
Yes. AT&T has always carried the iPhone since 2007.
AT&T doesn't sell the iPhone 3GS in white.
You need to have AT&T to own an iPhone.
No you can't. Only A T and T
AT&T.