Opt-out keyword

Messaging has an established convention — STOP, UNSUBSCRIBE and a handful of others, honoured automatically by carriers. Voice has no equivalent. A recipient revokes by saying "take me off your list" or "don’t call me again" or simply "stop calling me", and there is no standard set, so the platform must match against a curated list of phrases in the live transcript.

Keyword lists have to be tuned in both directions. Too narrow and a genuine revocation phrased slightly differently is missed. Too broad and a bare "stop" — which frequently means "stop talking for a second" — suppresses a customer who never asked to be removed. Requiring phrases rather than single common words is the usual compromise, with guardrails preventing anyone from adding an overly broad term.

Detection is only the first half. The revocation must be written to the internal suppression list, applied across every channel the organisation uses rather than only the one it was received on, and recorded with a timestamp and the utterance that triggered it. A revocation that stops today’s call but does not survive into tomorrow’s campaign is worse than none, because the recipient has been told they were removed.