what will happen if i stop payments for contract?

Hello!

let's say I bought a phone from AT&T with 2yr contract and will stop payments for it after a month. what will happen here?

thanks!

After a while AT&T will send your bill to a collection agency. If you do not pay this bill it will eventually ruin your credit - something you do not want in the long run.

well. in case i don't care about my credit history i can do that easily. thanks

P.S. i do care about it btw

Avenger is right.
They can send the entire amount of the contract, pro-rated, to a collection agency to collect the money they would have gotten from you over those two years.
Better off just paying the early termination fee and be done with it.

i can't find information about this "early termination fee". what is it?
I assume it will at least cover difference between retail price for the phone and special one (with contract), right?

It varies, but it's usually between $150 and $300.
For AT&T, it looks like it's about $175
PLAN TERMS | AT&T

Thanks, got it. But if I will but an iPhone with contract - do I need to return it if I terminate contract earlier? What if I will not return it?

I don't think so. They usually don't want the equipment back, that's the most part of the money they want for the contract, to cover the equipment.
It may run a bit more for the iPhone termination, because the phone is more expensive.
Another way you may be able to get around the fee, or a reduced fee, tell them that you just got a new job, and you are moving to an area where AT&T doesn't have coverage.where you are going to move
AT&T Coverage Viewer
Check here to find dead spots. Not saying it's going to work, but hell, it's worth a shot!