Unlocking an under contract AT&T iPhone 4S?

Is there any way to unlock it, without contacting AT&T and that doesn't cost a ridiculous amount? I switched to StraightTalk, if that matters.

No, you can go to a local store where they do factory unlocks which will cost you around 30-80 depending on the store.

Basically the cheapest way not involving AT&T themselves will be to get your 4S unlocked at one of the big online vendors like http://www.cellfservices.com/ as this will be significantly cheaper (and faster) than having it done in a local phone repair shop.

Here it is: http://senseiphone.com/unlock-att-iphone-imei-08294523/

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See the review posted there.

You dont need it unlocked to use straighttalk

Follow the safe and easy unlock guide for iphone 4s:
http://www.monitoring-softwares.com/how-to-unlock-iphone.html