Reminds me of the old collect call trick. Rather than state your name when prompted you transmit a short, perhaps even coded, message. Then the receiving party declines the call.
I recall using this occasionally in the 90s even.
There was also a period where I would regularly "one ring" my parents as code to call me back. IIRC that was because my cell plan had unlimited (or at least more) incoming minutes.
Collect calls would have been a thing until cell phones got very common because you had to use pay phones when you were outside and you somehow never had quarters.
