Multiple secondary device call controls and protocols

To control secondary devices of a subscriber whose primary device is subscribed to a mobile network, a secondary mobile directory number ("MDN") and secondary device identifiers are employed. After the primary device is rung, an Authentication and Call Waiting Engine receives a request from a Telephony Gateway to retrieve identifiers of any secondary devices that are linked to a primary MDN of the primary device. Next, the Authentication and Call Waiting Engine retrieves a secondary device identifier for each secondary device that is paired with the primary device by searching a secondary device identifier database with the primary MDN to find all linked secondary device identifiers. A rules database may be applied to exclude secondary device identifiers based on time of day and day of the week. The Authentication and Call Waiting Engine transmits the list of qualified secondary device identifiers to the Telephony Gateway for ringing.