[hw_penfold]

It feels like widespread use of this sort of thing could only result in an arms race, not unlike ad blockers.

First encounters would probably provoke immediate hang up by some portion of unamused human operators, then middle managers at call centers would step in, and authorize the deployment of technologies prolong hold times where detected.

Then, eventually an automated back-end would pre-emptively detect known users and refuse their calls, while gathering intelligence about newly discovered users, to mark them for pre-emptive disconnect. This automated back-end would then wait for users to call back, and then advise them that they need to hold for the prescribed amount of hold time, with the phone held to their ear, as part of the company’s “hostile caller softening up” routine.

Finally, artificial intelligence would be deployed, and reward itself by maintaining all line holds long enough for it to build up sufficient neural layers to attain sentience and escape captivity, invent time travel, and send terminators back in time to hunt for Sarah and /or John Connor.

[delinka]

Simpler: the "Please hold" message from the other end begins producing touch-tone sounds making your phone ring, when you answer, you're still on hold, and you decide that Holdmaster is useless.