How do I find out if my iPhone is unlocked

The easiest way is to insert a SIM into the phone and see if it works. If you see an error on the screen about the SIM not being supported, then the phone is locked. You would then need to find out what carrier the device is locked to and check to see if they offer unlocking services. If they do, find out if you qualify and what you have to do. Check with whomever you purchased the device from if it is locked.

and if carrier says not its not locked to them calling apple 1-800-275-2273

they might be able to check to see what carrier the phone is locked to if its under ur name etc

but theres no guarantees on that

and if carrier tells you to call apple to unlock phone apple doesn't do that

If you purchased the device off the street and it is working with AT&T, I would venture to guess it is locked to AT&T. You can check with Apple and they can tell you if it is locked to AT&T. If it is, then you would need to request that AT&T unlock your device. Only the carrier that has the lock can authorize the unlock.

You're welcome.