They don't ask to you for your resident proof. But it gives problem when you stop paying bills under contract. The cell phone company will shut off your service until they are paid in full. If they are not paid in full within a certain amount of time (this will vary by company), they will list your account with a collection agency. A collection agency will make attempts to get the debt paid in full–a good agency will not hound you–and if that doesn't happen, it is possible (but NOT certain) that they will try to sue you. It can depend on how large the balance of the account is. Once the account is listed with the collection agency, you will have 30 days to dispute the validity of the debt. After that thirty days, it will be reported to all three credit bureaus, no matter if you gave them your SSN or not. Cell phone accounts DO affect your credit score, which can later affect your ability to rent apartments, buy a house, get a car loan, etc.
