Can I buy a iphone without a contract, then update my current contract to use it?

I have a blackberry torch 9800 its garbage ever since I got it, it has had software problems and will not work.AT&T said the warrenty would not cover it because of 3 scratches on the top of the phone it passed all of the other tests but did not pass the cosmetic test, so can I buy a iphone from AT&T, then transfer my contract to use it

Starting off, that's really odd that AT&T voided your warranty because of scratches. The only thing that I've seen in their policy that definitely voids a warranty is water damage, and if your phone is coming up clean (as in, the damage 'dot' isn't pink,) then you should have your phone replaced under warranty.

I know that's not specifically what you want to do here, but I'd speak to someone else, perhaps a store manager or someone higher up. I've always had problems with AT&T when it came to phone upgrades and replacements. They always come up with some BS story about 'Oh, we don't do business with them anymore,' or 'They don't even make this phone and you aren't due for an upgrade till such and such.'

Whatever.

Under your circumstances, again, speak with a higher up. Explain to them that your phone is under warranty and you're under a contract. You would like to purchase a new iPhone instead of another Blackberry. Because you already have the data plan, it should transfer over no problem, but I'd still want to see about that supposed 'voided' warranty they're telling you you have.