One or more computing devices, systems, and/or methods for securely verifying devices such as protected are provided. A code may be generated for a first device. A short message service (SMS) message comprising the code may be transmitted to the first device at a mobile directory number of the first device. An entry may be created to associate the code with the mobile directory number. A determination may be made as to whether a first code within a message associated with the mobile directory number matches the code within the entry. In response to a match, the message may be processed and a status of the first device may be marked as valid, otherwise, the message may be rejected.