A method for adding an additional endpoint for a service based on a short messaging service (SMS) message may include receiving a request to add a second user equipment (UE) as an additional endpoint for a service associated with a first UE, and generating a transaction identifier in response to receiving the request. The method may include sending a command to provide a short message service (SMS) message to the first UE requesting permission to add the second UE as the additional endpoint, and receiving a message granting permission to add the second UE as the additional endpoint, where the message may include a network identifier assigned to the first UE. The method may include generating credential(s) for authorizing the second UE to access the service, and may then provide the credential(s) to the second UE.