How to have an iPhone without a data plan?

My current phone is terrible. I'm on ATT and recently went into the store and asked them to move my current plan (without data) onto a iphon 4 i was given. They said this was impossible because when the sim was put into the ihpone it would scan it and add a data plan automatically, although I have heard of ways of "unlocking" the SIM which would allow me to do this. Does anyone know of making this work, a differnet way to address att to convince them to let me do this, or of another carrier who would let me?

I would just like to have an ihone without a data plan with my current texting and minutes plan on it!

If it is impoortant, the iphone i was given was originally on tmobile

Why don't you go to your nearest Walmart and ask about "StraightTalk"? IIRC, they have an agreement with ATT AND Verizon meaning you get both coverages with no extra charge. They (Walmart) might be able to change you from ATT to StraightTalk keeping your number and worst case scenario they just give you (or you can buy it) a new SIM card and new number… Plus, it's not a plan, you buy a card every month they have from I think ~30 a month to over 100 bucks for an entire year and just add it to your account. I have StraightTalk and I'm quite happy with it, for just $45 a month I have unlimited text, talk and data, nationwide.