Within 10 business days. Under FCC rules a reply like STOP, QUIT or CANCEL counts as an opt out, and you have to honor it within 10 business days. The wider "revoke all" rule was pushed back to January 31, 2027.
Best practice is to stop right away. Most texting tools do it automatically when someone replies STOP, so check that yours is turned on.
When the revoke all rule starts, one opt out will cover every kind of marketing message from you, not just the channel they replied on. Plan for it now.
A do not call request has to be honored for 5 years, so keep a list and scrub every lead against it before you dial. This is a summary, not legal advice.
Updated October 2026. Industry ranges from public lead and commission guides. Your results depend on your carrier, contract, and dialing.