1. Any reply containing STOP, SIMAMA, ACHA or ONDOA — in any case — is an opt-out.
2. Mark the number as opted out in the application the same working day, and never later than 24 hours.
3. Send one confirmation: "You will no longer receive Org messages. Reply START to rejoin."
4. Opted-out numbers are excluded from every bulk send automatically; check the exclusion before each campaign.
5. Service messages the person cannot reasonably refuse (e.g. an emergency at school) may continue — say so in the consent form.
6. Keep the opt-out record for at least 12 months.