M500FPJ; The M500FPJ Addressable Firephone Control Module gives Johnson ControI�s IFC control panels the capability to monitor and control a circuit of up to two firefighter phones. The M500FPJ has the ability to differentiate between normal, offhook, and trouble conditions. This module is used to connect a remote firefighter telephone to a centralized telephone console. A ringing sound is provided at each off-hook handset until it is connected to the console. The user can then connect that offhook phone to the main riser for the voice evac system.