Why your texts to clients stopped arriving

Your client says the inspection reminder never came. You open the thread, and there it is. Sent. Same as every other message, with nothing on it to say anything went wrong.

"Sent" is the problem word. In the definitions Twilio publishes for its own service, sent means the nearest carrier accepted the message, and delivered means the carrier confirmed it reached the phone. Everything that goes wrong happens between those two words. Some tools only ever show you the first one.

There are five usual causes, and they need different fixes. Your number isn't registered. The wording got filtered. The client replied STOP. The number is wrong or a landline. Or it's the carrier. The test below sorts them out in about five minutes, and you should run it before you re-send anything, because re-sending to someone who opted out is the one mistake here with a price per message.

30034

sent from a number with no approved registration

30007

filtered by the carrier or the provider

21610

the recipient replied STOP

30006

a landline, or a line that can't take texts

These are Twilio's codes. Other providers number their errors their own way, so check your tool's help pages for the match.

The five-minute test

You need your texting tool open, your own phone, and one colleague whose phone is on a different carrier from yours.

1. Does the message say "delivered"?
   • If yes: the carrier handed it to the phone, so look at the phone. An iPhone with Screen Unknown Senders turned on puts texts from numbers that aren't in Contacts into a separate list. Ask your client to look there and save your sending number as a contact. You're done.
   • If no: if there's an error number, match it to the four above and go to that cause. If it only says sent, keep going.
2. Did the client ever reply STOP, END, QUIT, CANCEL, or UNSUBSCRIBE? Search the whole thread, including last year's deal.
   • If yes: that's the answer. Nothing goes through to that person until they text START themselves. Don't try a second number. Call or email, and if they want texts back, they reply START.
   • If no: go to 3.
3. Call the number. Does your client pick up on a mobile?
   • If no: a desk phone, an office line, or the wrong person. A landline can't receive a text. Fix the number on the file and send again.
   • If yes: go to 4.
4. Send the same message, from the same tool, to your phone and your colleague's. Does it reach both?
   • If neither gets it: it's registration. Skip to the next section. That's the slow one.
   • If only one gets it: go to 5.
   • If both get it: your registration and your wording work on those two carriers. Go to 5 and send the plain version straight to your client.
5. Strip the message down: your business name first, no link, nothing but the facts. Does the plain version arrive where the original didn't?
   • If yes: it was the wording. The usual culprit is a link from a public shortener, which carriers treat as a spam marker and filter with no recourse. Link to your own domain instead.
   • If no: it's the carrier. Send your provider the time, the number, and the message. That one is theirs to chase.

If step 4 failed: registration

Business texts sent by software over an ordinary local number are application-to-person (A2P) messaging on a ten-digit long code (10DLC), and they have to be registered. Since Feb 1, 2025, the major US carriers block unregistered 10DLC traffic outright. Some providers cut it off earlier. Twilio blocked it on its own network from Sep 1, 2023.

A text you thumb into your own phone is person-to-person, and none of this applies. The moment a program sends on your behalf, it does.

Registration is two filings, and people tend to finish the first and assume they're done.

The brand says who is sending: legal name, employer identification number (EIN), address, and a contact. If you don't have an EIN, there's a sole proprietor route: one phone number per campaign, and a code sent to your mobile that you have to answer within 24 hours.

The campaign says what you send: sample messages, how often, and how people opted in. A verified brand with no approved campaign still can't send a thing.

The money is small. On Twilio, brand registration is $4 one-time for a sole proprietor or a low-volume business and $44 for standard, each campaign costs $15 to vet, and the monthly campaign fee runs $1.50 to $10. Your provider may bundle these differently.

The time is what hurts.

Brand approval minutes

Campaign review 10–15 days

First text that arrives day 11–16

day 0day 16

A rejected campaign goes back to the start of the middle bar.

Brands are typically approved within minutes, and campaign reviews take 10–15 days. A rejection puts you back at the start of that wait, and campaigns get rejected for paperwork. The two reasons to fix before you file:

• The opt-in wording. The consent language has to say what kind of messages, how often, that message and data rates may apply, and how to opt out, and it has to sit right next to the checkbox, not in a linked document. "I agree to the Terms of Service" doesn't count.
• The privacy policy. It has to say you don't share mobile numbers or consent with third parties for marketing. A policy that allows sharing "with partners" gets bounced.

Consent lives on a screen, not in a conversation

A phone number on a signed listing agreement is a contact detail. A verbal "sure, text me" is real and undocumented, and the documentation is what anyone will ask for. A client who texts you first has invited your reply. We wouldn't stretch that to automated milestone updates from software, and we wouldn't want to argue it to a campaign reviewer.

What holds up is a checkbox with the wording above and a time recorded.

STOP is where agents get into money. Since Apr 11, 2025, people can revoke consent by any reasonable means, including replying STOP or QUIT, and you have no more than ten business days to honor it. The rule that makes one STOP cover everything you send, on every topic, has been pushed to Jan 31, 2027. Treat it as in force now. The past buyer who said STOP during escrow did not mean "except when I sell."

Under the Telephone Consumer Protection Act (TCPA), damages start at $500 per violation and a court can triple them for willful ones. Two hundred texts to people who never agreed is $100,000 at the minimum.

This is an operating guide for US texting, not legal or compliance advice. Carrier rules move, and the dates above have moved before. If you're texting anyone who didn't ask, that's a conversation with a lawyer, and no registration fixes it.

The part that never ends

Filing once is manageable. Keeping it true is the job: a registration that stays approved, a timestamp behind every consent, and a STOP that works at 11 p.m. without anyone remembering to act on it.

We went through carrier registration for KeyFlow's own sending number, so texts KeyFlow sends go out on our registration, not one you have to file. Today those texts go to you and the people on your team: a digest of unread team messages and upcoming milestones, daily or weekly, at the send time you pick. Each person adds their own mobile number and ticks a box that starts unticked, names KeyFlow, says how often texts come, says reply STOP to opt out, and says message and data rates may apply. We record when they ticked it. A reply of STOP turns it off and records when; START turns it back on. Anyone without consent on record is skipped, not texted. Replies other than those two words aren't collected anywhere, so it isn't a way to chat.

KeyFlow doesn't text your clients.

For them, the deal lives on a page instead. You copy one link, they confirm their last name, and they see the closing date, the closing path, what you still need from them, and their files. You still have to get the link to them once. After that, whether they know where things stand doesn't depend on a text making it past a carrier.

Run step 4 this afternoon

Send one message from your texting tool to your phone and to a colleague on another carrier, today, while nothing is riding on it. If neither arrives, start the registration now, because you're looking at two weeks and a closing won't wait for them.

Then keep three rules. File before a deal needs it. Get consent on a screen with a time on it. And when someone texts STOP, that's the answer for the next deal too.

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Sources: Twilio: message resource and delivery statuses · Twilio: error 21610, unsubscribed recipient · Twilio: error 30006, landline or unreachable carrier · Apple Support: view conversations from unknown senders · Twilio Help Center: sending shortened links · DailyStory: what is 10DLC registration (2026) · Twilio changelog: full blocking of unregistered 10DLC · Twilio: sole proprietor registration overview · Twilio: 10DLC pricing · Twilio: A2P 10DLC registration quickstart · Twilio: error 30924, consent language · Twilio: error 30908, privacy policy · Bryan Cave Leighton Paisner: TCPA opt-out rules effective Apr 11, 2025 · Wiley: FCC extends waiver of the consent revocation rule · Legal Information Institute: 47 U.S. Code § 227