Put a AT&T SIM Card From Other Phone into Iphone???

[crystalized]

I have a normal cellphone with a 3G at&t sim card in it. I'm thinking about purchasing an unlocked and jailbreak 3G iphone from craiglist.

I've been reading a lot of different things and it sounds like I can put the sim card in there without any trouble as long as its unlocked and jailbreaked.

But I've also been seeing comments about how at&t can tell if you switch phones and start using an iphone and they will change your phone plan. Is this true?

I just want to be able to call people on the iphone like I would with my normal phone. I'll only use the other stuff when I'm near a wifi spot.

If it is true, then I may just have to settle with using the iphone like an ipod and not a phone.

[eyeRobot]

It's not true. you'll be fine.

When I was on holiday in the US last month I had a prepaid AT&T card which worked on my previously unlocked AT&T phone. I used it for phone, messages and data no problems.

[crystalized]

TXT and e-mail from AT&T regarding "ineligible" data plan with iPhone 3G

From what i've been reading all over the internet is that it will work, but they will eventually detect you and start charging you. The imei on a 3g or higher iphone cannot be spoofed because a hack was never created for it and therefore at&t will be able to detect that you've switched phones.

I think they only monitor the iphones. You wouldn't have a problem if this was any other kind of cellphone. But they guard their precious iphones jealously.

[eyeRobot]

I think you will be ok with prepaid, but seemingly not on a contract.