No. You are on-contract with AT&T for 2 years. You are not tied to that specific phone for 2 years. There is nothing stopping you from buying any unlocked GSM full-price, from AT&T, an online retailer, or eBay, moving your SIM card over, and happily enjoying your new phone. At any time.
That's the beauty of GSM, and one of the reasons I am with AT&T and not Verizon. People are so used to the Verizon "rape the consumer" way of doing things that sometimes they can't fathom how the rest of the world (which is almost entirely GSM) handles cell phones.
my friend has taught me that as long as i have five lines on my phone, i can just purchase the phone at 2 year pricing....
Granted, i would have to change my plan into a family plan
but i initially had an Xperia/Captivate(thirty day exchange)
on the line i signed up with....
I wanted to try an iphone 4...so i got it on the second line..
got bored with the iphone 4
so i sold it and made more money on it then i actually spent
now with line 3 i have the backflip
and once WP7 comes out, i will have line four
I will then be selling my captivate for hopefully 300(although, my friend only made 260 off it) and then my backflip for 100 bucks!
All in all, my plan has the lowest minutes possible because
90% of my friends are at & t customers and i have the favorite
five for the others who aren't
with texting and data package
my plan is like 119 i think before employee discounts