Systems and methods for activating a mobile device for use with a service provider are described. In one exemplary method, a mobile device having a currently inserted SIM card may be prepared for activation using a signing process in which an activation server generates a signed activation ticket encoded with SIM policy data that corresponds to the combination of the device and one of a number of SIM cards belonging to a set of SIM cards defined by the SIM policy data. The activation ticket is securely stored on the mobile device. In another exemplary method the mobile device may be activated in an activation process in which the device verifies an activation ticket against information specific to the device and SIM card in accordance with the SIM policy in the activation ticket, and initiates activation when the verification of the activation ticket is successful.