Additionally, in my town, the tones apply to pagers the volunteer depts use to alert their members of a call and the town stopped using street sirens to alert the volunteers. But they can also be used to activate receivers on street sirens, garage door openers, firehouse lighting… anything you can think of actually. The tones consist of two separate tones which are activated together, at the same time. The use of two tones is to eliminate any false activation that might happen with a single tone… and a specific duration of time they sound (in seconds) is also stipulated when programming the receivers. In my town that time is set to 8 seconds… longer than most normal setups, the pagers have to see a full 8 seconds before they activated. But that 8 second duration was due to a concern (which proved to be unfounded) that amateur radios could be used to transmit these tones without authorization, malicious activity. Amateur radios may be able to transmit the tones but apparently, not for 8 seconds. At least that’s what we were told.
Using a scanner for this purpose defeats the purpose of the scanner. That’s because the scanner must be set to “Hold” on the frequency the audible tones are transmitted on, while waiting for the activation tones. The radio stays muted until the tones activate it and anything else you programmed isn’t scanned. It’s the same process a weather alert radio uses… it also just sits there muted until the activation tones are transmitted.
