SMS Compliance and Deliverability: Why Business Texts Don’t Get Delivered

When a text from your business never arrives, it is almost never random. Carriers decide every message, and they block for a handful of reasons:

• The number isn’t registered. US carriers block business texts from local numbers that aren’t registered for A2P 10DLC. Our 10DLC guide explains registration step by step.
• The message looks like spam. Carrier filters score the wording: hype words, ALL CAPS, “!!!”, public link shorteners and topics carriers restrict.
• The message doesn’t match what you registered. A number registered for appointment reminders that starts sending promotions gets filtered.
• The person can’t receive texts. Landlines, disconnected numbers and phones that are off or out of coverage.
• The person opted out. Once someone replies STOP, the carrier and your provider stop delivering to them from that number.
• Sudden volume. A brand-new number that suddenly sends hundreds of identical texts looks like a spam run, even with good intentions.

When a text fails, your provider usually returns a code. These are the most common ones (Twilio’s codes; other providers use similar ones):

In Conduyt, a refused text shows as Not delivered with these reasons in plain English and the carrier code alongside, and a line the carrier refused because it can’t text isn’t used again for an hour.

Three layers of rules apply to US business texting. This is a plain-language summary, not legal advice; check anything specific with your counsel.

1. The law: TCPA and state laws

• Get consent first. Marketing texts sent through software need the person’s prior express written consent: a form checkbox, a signed agreement or a keyword they texted in. Informational texts (appointment reminders, order updates) still need consent to contact them.
• Honor opt-outs. Under FCC rules, replies such as STOP, QUIT, END, REVOKE, OPT OUT, CANCEL and UNSUBSCRIBE count as an opt-out. Stop texting right away. One confirmation text is allowed, with no marketing in it.
• Respect quiet hours. Federal rules limit telemarketing to 8 AM to 9 PM in the recipient’s local time. Some states, including Florida, Oklahoma and Maryland, have their own stricter texting laws, such as an earlier evening cutoff and limits on repeated sales messages.
• Don’t text numbers on the Do Not Call list for marketing unless that person gave you consent.

2. The carriers: A2P 10DLC registration

AT&T, T-Mobile and Verizon require every business texting from a local number through software to register its brand and use case. See What is 10DLC?

3. Industry guidelines (CTIA)

The wireless industry’s messaging principles set the practical rules carriers enforce: a clear call to action when people sign up, consent for each program (not one opt-in reused for everything), a confirmation message, working STOP and HELP keywords, and no buying, renting or sharing lists.

The opt-in is where most compliance problems start, and it is also what carriers check when you register. A good web form opt-in states, next to an unticked checkbox:

• Your business name and what you will text about (for example appointment updates and offers).
• How often (for example “up to 4 messages a month”).
• “Msg & data rates may apply.”
• “Reply STOP to opt out, HELP for help.”
• Links to your terms and your privacy policy, and a line that mobile numbers aren’t shared with third parties for marketing.

Then send a confirmation as the first text: who you are, what they signed up for, and how to stop. Keep a record of when and where each person opted in; it is your proof if anyone asks.

• Lead with your business name: “Sunrise Realty: …”.
• Include “Reply STOP to opt out” on the first text to each person, and every so often after that.
• Keep it to one segment when you can: up to 160 standard characters, or 70 if the text has an emoji or special character.
• Say a flagged word once, not three times. Words like “free”, “cash” or “loan” are fine in a legitimate text; repeating them adds up.
• Use your own domain for links, never bit.ly-style shorteners.
• Skip the hype: ALL CAPS, “!!!”, “act now” and “guaranteed” read as spam to people and to filters.
• Age-restricted products (alcohol, tobacco and vape, firearms, gambling) can be texted when your campaign is registered for them and your contacts are confirmed adults. Cannabis, illegal drugs and sexual content aren’t allowed on US business texting.

Our free text message checker does all of this in one click: it underlines risky words, counts segments, and checks for your business name and the opt-out line.

1. Your texting number is registered for A2P 10DLC (or verified toll-free), for the use case you actually send.
2. Every contact you text opted in, and you can show when and where.
3. Your opt-in shows your name, what you send, how often, “Msg & data rates may apply”, STOP/HELP and links to terms and privacy.
4. Your privacy policy says mobile numbers aren’t shared with third parties for marketing.
5. STOP and similar replies stop all texts right away, and opted-out contacts are flagged in your CRM.
6. Marketing texts go out between 8 AM and 9 PM recipient time, earlier in stricter states.
7. Each text names your business; the first includes “Reply STOP to opt out”.
8. No shared, bought or rented lists.
9. Failed texts are reviewed by error code, not ignored.

For the outreach side (when to text, what to say, how it fits with calls and email), see our B2B SMS outreach guide and CRM text messaging.