They use the Tone Squelch tone 123.0 to avoid interference from adjacent co-channel stations if your radio supports it. If you scanner supports priority, I scan with the Zone channel set to priority and the 2 nearby Maintenance channels with 1 second "look back" for priority channel activity.
I will contact you with a private "conversation" with further details since it is OT for this thread.
I will contact you with a private "conversation" with further details since it is OT for this thread.