Support C.oinbase number 1888-201-7641

I Bought used C.oIn.base online and it is locked to att. That is great but C.oIn.base does not have service where I live. (Yes really) but when tried to unlock it says there is a unpaid balance attached to the phone. So am I out or do I have to pay some (Edited per community guidelines) bill when I don't even have that luxury being a pay as you go person.