When I used to work as a courier, our Yaesu and Midland radios had a
"Tone" switch on them. When the tone was off, I could hear all the
other users on same frequency. However, of course, when the tone was
on, only our company could be heard. When I monitor the courier
company I used to work for, with my scanner that is not CTCSS
equipped, I will hear all the other users on that frequency.
Fred Burgess
In a CTCSS receiver, the squelch does not work based on the strength
of the signals. Instead the transmitter send a continuous sub-audio
tone of a particular frequency during each transmission. The squelch
on the receiver will never be broken unless it detects that particular
tone in a transmission. At that time you will still hear all the other
communications on that channel. In the case of CTCSS however, the
transmission you want to listen to could actually be weaker than some
other transmissions, and thereby very hard to understand.