CAVERN Network • Audible Signal Tones

CAVERN Network Control, Group Leaders and Volunteer Emergency Radio Network operators (with a GMRS radio+license) can use audible DTMF tones as signals over the network to get attention and indicate various conditions. When these audible tones are heard, it encourages others to be alert for additional information (especially during emergencies).

These tones are sent using the radio’s numeric keypad:

CAVERN’s standard GMRS radio, the BTECH GMRS-V1

NOTE: CAVERN’s Retevis RT-22 FRS radios are NOT able to transmit tones (no keypad).


The two basic audible tone signals proposed for the CAVERN network are:

(1) HELLO Signal

Keys                                                  Name                                      
 #                                                     “HELLO

Hold key down for four-seconds (count up to “four-one-thousand”)
• Standard ‘pay attention‘ signal, used to start meetings, check-ins, etc.

NOTE: This HELLO signal often precedes other signals! During a Fire, a HELLO signal sent late at night before an “everything’s OK for now” update may be shortened to ~2 seconds.

(2) EMERGENCY Alert Signal

Keys                                                  Name                                      
 # * # * # *# *                                “EMERGENCY

Only sent to Emergency Alert Channel (FRS 9, GMRS 33).
Only sent by Net Control or a Group Leader (with a GMRS radio).
• Alternate “pound” and “star” keys (like an ambulance siren).
• Each keypress is less than one (1) second.
• Pause for one second between pairs.
• Four (4) repetitions of the tone-pairs is sufficient.

NOTE: If you hear this signal, it means there is a serious emergency somewhere nearby! After this signal, there will be additional information transmitted over the Main Repeater Channel (FRS 8, GMRS 23), including the incident location. Do more than just listen: you should get ready to move fast in case it’s somewhere near you!

SPECIAL SIGNALSNetCon & Group Leaders

Three (3) special audible signals are for Network Control & Group Leaders. Most CAVERN operators will not send these and those with Retevis RT-22 FRS radios cannot send them (though they can hear them).

(3) Danger Level Signal

Keys                                                  Name                                      
 ### ### ### ### ###           Danger !
###  ###  ###  ###  ###  ###  ###  ###  ###  ###   HEY !!

• Press “pound” key 3x rapidly (a ‘triple-tap‘)
• Pause for one (1) second between each ‘triple-tap’
Repeat ‘triple-taps’ 5x-10x (more indicates higher danger)
• 10x = highest possible danger level (catastrophe: almost never used)

NOTE: These signals are sent by Network Control
   —> Only to the Emergency Alert Channel (FRS 9, GMRS 33)
—> Only when there is useful incident info
   —> Followed by:
            A brief incident summary.
            More info on CAVERN Main (FRS 8, GMRS 23)

(4) Group Leaders / GMRS “Gather” Signal

Keys                                                  Name                                      
  88 33 77 66                                 Power Rangers Combine!

• ‘Musical’ tone for NetCon/Group Leaders to call all GMRS operators*
Press & Hold each key Twice (2x) holding for a half second each
Pause 1 second between pairs

NOTE: Spells “VV EE RR NN” for Volunteer Emergency Radio Network operators.
* GMRS operators are the network‘s backbone, leading the groups and relaying other people who cannot be heard: this calls them together for something important.

(5) Test Signal

Keys                                                  Name                                      
  218 218 218                                Start Test / End Test

Used by operators to: test the Repeater and train on using signals.
Press each key Twice (2x) holding for a half second each press.
Pause 1 second between pairs.
Preceded by saying “START Test Alert” out loud.
 • Followed by saying “Test Alert END” out loud.


First, set your radio to the CORRECT CHANNEL!

Next, generate the DTMF audible tones (on a BTech GMRS V1 radio) by holding down the upper Transmit Button (on the left side of the radio) and pressing keys as described in the sections above.

 Hold down Transmit       Press “Star“,”Pound“, etc

PRESS quickly on a key for a SHORT tone.
HOLD down a key to send a LONGER tone.
Use the Number keys to send the ‘musical’ signals.

Leave a Reply

Your email address will not be published. Required fields are marked *