Did you know?: The beeps that you hear every 20 minutes on the rig radio is a required FCC Identifyer. Is there a way to shut it off? Yes. Press the Mon (Monitor) button. Frequencies may be issued to different agencies, a PL (Private Line Code) seperates the agencies. In the above frequencies you will see TPL 85.4, that is the private line code assigned to that frequency for FDNY only. The radio programmer puts that code in with the frequency and you will only hear other radio's that have that code. CSQ (Carrier Squelch) means there is no PL code, so you hear everything. The Monitor button opens the PL, so you will hear the FCC Identifyer beeping. When you press Monitor button and the screen says Monitor on, you won't hear it. This button is easily accidentally pressed by the boss or company chaufeur. I KNOW, major nerd knowlege. But you will be happy when you secretly press it and stop the beeping.