CTCSS Just sets a squelch tone to send your transmission, it can still be listened to you just can't transmit unless you have the same tone, but even then some devices can show you the tone that transmission is set to
Back in the olden days, when PMR446 had 38 CTSS codes, before DCS was added making 121 codes, that people
thought were sub-frequencies …..
There were also toy & other cheap PMRs without the CTSS function.
I had a few Tesco stripey label PMRs which I would use to supplement our main PMRs.
The lack of CTSS did not mean that channel 1.01 to 1.38 were unavailable, but that the cheap PMR didn’t know that it should not pick them up on 1.0
I could then allocate CTSS numbers to people, such as compressed air station (who had a habit of going to Vox and blocking the airwaves when running the compressor), another CTSS to safety Marshalls, another to game control Marshalls, another to the safe zone and one each to faction leaders.
That way each CTSS group could have their own conversations whilst I could track them all or anyone could contact me.
Then I’ll pull out my proper PMR and switch to the appropriate CTSS
(The cheap PMR would only transmit on .0 rather than to the CTSS codes, but could hear everything from .0 to .38 as long as you were on the right core channel