A wireless emergency alert system (also known as a wireless emergency alert system, or “WEA,” and formerly known as a commercial mobile alert system, or “CMAS”) receives a geotargeted federal alert that is to be delivered to mobile devices within a defined geographic region. A database of locations of access points is utilized by the system to identify those access points that are likely present in the defined region. The system identifies mobile devices that have an ongoing connection (e.g. IP multimedia subsystem (IMS) session) with the identified access points, in part by maintaining and accessing a look-up table containing location information for the access point and connected mobile devices. In addition, the system tracks mobile devices that no longer have an ongoing session and deregisters the appropriate mobile devices in the look-up table. For mobile devices that have an ongoing session, the system delivers the received alert to the mobile devices in the targeted region via the identified access points.