A marketing text arrives in the most personal inbox a person has. Regulators and carriers treat it accordingly: in many markets SMS requires express written consent, quiet hours are enforced, and a single complaint can trigger questions a brand must answer with records, not recollections.
Most SMS programmes collect consent casually and store it worse. The fix is unglamorous record keeping, built at the moment of signup, when the evidence is free.
What counts as consent for texts
The standard in strict markets is express consent for marketing messages: a clear, affirmative action, signing up for texts specifically, with the programme's nature disclosed. A phone number handed over for delivery updates is consent for delivery updates, not for a weekly promotion stream.
Pre ticked boxes and bundled consent language fail here in the same way they fail elsewhere, only faster, because SMS complaints go to carriers and regulators who ask for proof early. The disclosure at signup should name the brand, the message type, and the expected frequency in plain words.
Double opt in earns its friction
Requiring a reply, typically YES, to confirm subscription feels like lost signups. What it actually filters out is mistyped numbers, other people's numbers entered as a joke or a grudge, and people who never meant to subscribe at all.
The confirmation exchange also creates a timestamped record in the carrier system itself, which is about as robust as consent evidence gets. Programmes that adopt double opt in consistently report cleaner lists and fewer complaints per thousand messages sent.
The record to keep for every subscriber
Store the number, the timestamp, the source, web form, keyword, point of sale, and a snapshot or version reference of the exact consent wording displayed. Add the confirmation exchange where double opt in is used, and every opt out with its timestamp.
Keep the record for the life of the subscription plus a defensible period after. When someone complains six months after unsubscribing, the record that answers in one email is the difference between a closed file and an investigation.
Opt outs must be instant and total
STOP style keywords must work immediately, across every campaign stream from that brand, not just the one the person replied to. Honouring opt outs slowly or partially is the single most common source of SMS enforcement trouble.
Send one confirmation of the opt out and nothing else ever. The programmes that get in trouble are rarely the ones that lacked a signup form; they are the ones that kept texting after the relationship was clearly over.
Related reading
These earlier guides go deeper on connected questions: Cookiebot Alternatives: A Practical Comparison A practical way to compare consent platforms side by side: blocking, records, pricing units, design control, and support, with a shortlist method any team can run., Consent in Companion Apps for Connected Devices Smart devices phone home through companion apps that track, sync, and share. Where consent should appear in that flow, and the dark corners most setups miss., and Consent and Email Preference Centers: Giving Subscribers Control Without Losing Them A preference center turns an unsubscribe into a choice. Designing consent options subscribers actually use, and honoring them everywhere the data travels..
Frequently asked questions
Can I text customers who gave their number at checkout?
Only within the purpose they gave it for, usually delivery and order updates. Marketing texts need their own explicit opt in. Treating a checkout phone field as a marketing list is the classic SMS compliance error.
How long is SMS consent valid?
Until the person opts out or the number changes hands. Numbers are recycled, which is another argument for periodic list hygiene and for double opt in, since a recycled number never confirmed anything.
What should the signup disclosure include?
The brand sending, that messages are marketing, expected frequency, that message and data rates may apply, and how to opt out. Short is fine; accurate is mandatory.
Are transactional texts treated differently?
Yes, order confirmations and delivery alerts under the original transaction usually follow lighter rules than marketing. The moment a transactional message carries promotional content, it tends to be judged as marketing, so keep the streams separate.