said by pepe1812934089 :

Nope. They won't do it. Not yet, at least. There's too much money to be made currently simply keeping the 3G iPhones on the ATT network.

Just keep paying the bills if you know you'll be coming back to the U.S. and find a phone you like for use back home. It seems like the way to go especially if you like the service you've enjoyed thus far w/ the 3G iPhone.

-Pedro

said by scots :

They are not unlocking the iPhone 3G. I recall seeing someone mention elsewhere that they asked about it and AT&T told them it couldn't be done.

I believe they have an option to put the account on hold where you pay something like $5 or $10/month rather than your regular monthly bill. This does have the effect of extending your contract by the number of months the account is on hold. So...if your contract is currently set to end in July 2010 and you put the account on hold for 5 months, your contract would then be extended to December 2010.

The ETF (should you choose to cancel) is pro-rated. It starts at $175 and is then reduced by $5 for each month you've been in the contract. In your case, if you canceled service on January 12 your ETF should be $145. July 12 through January 12 would be 6 months * $5 = $30 off the ETF.

If you did cancel and then come back you shouldn't be under another contract when you come back if you use your current phone rather than getting a new one. You would lose your current phone number, though.