I currently have a legit activated OOB 1.1.2 w/3GPP NextSIM on T-Mobile and it works great. No Jailbreak or 3rd party apps.

I want to use iTunes to update to 1.1.3 then borrow a friends active AT&T/iPhone SIM put it in my iPhone and activate my device via iTunes. Then put my 3GPP/NextSIM w/T-Mobile SIM back into the iPhone.

Anyone done this? I've searched but it's hard to define this in a search.

I don't need or want my phone jailbroken, i just want the full version of 1.1.3 with location etc.