Upgrading from unlocked iPhone to iPhone 3G

[shabutie]

I'm just curious on this issues.
I did my research, searching this entire forum and didn't find a post that satisfied my curiosity.

My friend gave me his old iPhone when he decided to upgrade to the iPhone 3G.

During this time I was using a Sony Ericsson phone through ATT w/ unlimated SMS/MMS and an odd amount of minutes, I don't quite remember. Anyways, when my friend gave me his old iPhone I decided to unlock and jailbreak it so that I could use it with the SIMS card from my Sony...

When I go to wireless.att.com and my account it shows I am using the iPhone and that it's "Active"

I've been using the old iPhone for about a month w/ no problems at all and now, since it says on my wireless account that I'm using the old iPhone, I wa wondering if I would be able to upgrade from this iPhone to the 3G iphone for the price of $199/$299 and then tell them I will activate/add data plan at home using iTunes/ my wireless att account online and just use the SIMS card from my Sony. Do you think this will work?

[Imahottguy]

If you fail to activate the 3G iPhone within 30 days, the credit card you used to buy it will be charged a penalty, which is rumored to be $300. I don't quite understand what you are trying to do. If you want the iPhone but don't want to extend your contract, then perhaps you should go to eBay, the B/S/T forums or Craigslist.

BTW: You do not need to unlock a 1st gen iPhone for it to work on AT&T, and not extend your contract. You only need to fake activate it.