A contract mobile phone or post-paid mobile phone is a mobile phone for which service is provided by a prior arrangement with a service provider. The user using this form of agreement usually is billed according to their use of mobile services at the end of each month. Typically, the customer's contract specifies a limit or "allowance" of minutes, text messages or mobile broadband and the customer will be billed at a flat rate for any usage equal to or less than that allowance. Any usage above that limit incurs extra charges which can sometimes be quite high, but theoretically, a user in this situation has no limit on use of mobile services and, as a consequence, unlimited credit.