Opt-out and consent, explained
Consent is permission a person gives to be contacted, and an opt-out is them taking it back. For sales and marketing messages both matter, and both are specific to a channel and a purpose: someone may be happy to get order updates on WhatsApp but not promotional SMS. A good record notes what the person agreed to, on which channel, when and how, for example the wording of the checkbox on the form they filled in.
In India, several rules point the same way. The Digital Personal Data Protection Act, 2023 expects consent to be free, specific, informed and unambiguous, and withdrawing it to be as easy as giving it. For SMS and calls, TRAI's rules let people block commercial communication through their Do Not Disturb (DND) preferences, and promotional messages cannot go to numbers that have opted out. WhatsApp requires businesses to get opt-in before messaging people and to honour requests to stop.
In practice: never pre-tick a consent box, keep the evidence with the contact, and treat every opt-out, whether an unsubscribe link, a STOP reply or a spoken request on a call, as applying at once across the whole team. A salesperson messaging someone from a personal phone after the company recorded an opt-out is still a breach. In DigiPix Flow, unsubscribes, STOP replies, bounces and privacy requests all land in the same place.