"squelch codes" probably conveys the meaning more correctly.
people understand the idiom that just because your radio has squelch set (too high, perhaps) that it doesn't mean someone else can't hear it.
otherwise, CTCSS codes works fine, that's the technical description of what it is. and actually they call them "squelch tones" there. it's only motorola that branded them as "private lines", that's their trademark for an adequately-described term. Much like Tesla "Full Self Driving"/"Autopilot", it's kind of a misnomer and definitely breeds (deserved) confusion.
people understand the idiom that just because your radio has squelch set (too high, perhaps) that it doesn't mean someone else can't hear it.
otherwise, CTCSS codes works fine, that's the technical description of what it is. and actually they call them "squelch tones" there. it's only motorola that branded them as "private lines", that's their trademark for an adequately-described term. Much like Tesla "Full Self Driving"/"Autopilot", it's kind of a misnomer and definitely breeds (deserved) confusion.
https://en.wikipedia.org/wiki/Continuous_Tone-Coded_Squelch_...