What is A2P 10DLC and why are business texts getting blocked?

A2P 10DLC is the carrier system for business texting from ordinary 10-digit phone numbers. A2P stands for application-to-person: a message sent by software (your scheduling tool, CRM or texting platform) to a person's phone. 10DLC stands for 10-digit long code, the standard local number format, as opposed to a short code like 55555 or a toll-free number.

Twilio's explainer on A2P 10DLC registration describes the rule plainly: US wireless carriers require businesses that text from these numbers to register their numbers and describe their texting use cases, with the stated goal of cutting spam and fraud. If your dental office sends appointment reminders, your law firm texts intake follow-ups, or your property management company texts tenants about maintenance windows, this applies to you.

The most common reason is that the number sending them is not registered, or is registered but not linked to an approved campaign. Twilio's own documentation for error 30034 says it blocks messages to US numbers when the sending 10DLC number is not tied to an approved A2P 10DLC campaign. Twilio's 2023 announcement set the date: after August 31, 2023, it would completely block all unregistered US-bound 10DLC messages.

The second reason is filtering. A registered number can still have individual messages blocked. Twilio's error 30007 page says a filtered message was blocked by Twilio's systems or by a carrier that flagged it as spam or objectionable. Content that looks like a phishing attempt, shortened links from generic link shorteners, or marketing sent under a campaign registered for appointment reminders can all trigger it.

The third reason applies to toll-free numbers. According to Twilio's error 30032 page, unverified toll-free traffic was blocked as of January 31, 2024. Toll-free numbers do not use 10DLC registration, but they have their own verification step, and skipping it has the same result.

Registration has two main parts, plus the technical step of attaching your numbers. Most texting platforms (Twilio, and the business tools built on top of carriers such as booking, CRM and phone systems) walk you through the forms, but the information has to come from you.

• Brand registration: your legal business name, address, contact details and business registration ID. Twilio lists a US EIN as the typical ID. The name and EIN must match what the IRS has on file.
• Brand type: Twilio's March 2025 approval guide notes that a business with an EIN cannot register as a sole proprietor. Sole proprietor registration is for individuals or very small businesses without a tax ID, and it allows only one number.
• Campaign registration: what you send (reminders, customer care, marketing or a mix), who receives it, sample messages, and how people opt in, opt out and get help.
• Number assignment: each sending number is added to the messaging service tied to your approved campaign. A number left outside that pool stays unregistered, even when the brand and campaign are approved.

Campaigns get rejected when a reviewer cannot confirm that your business is real and that recipients agreed to hear from you. Twilio's guide to improving approval chances lists the patterns it sees most often, and each one is fixable before you submit.

• Website problems: an empty site, a site under construction, a password-protected page, or a domain that does not match the business name.
• Privacy policy gaps: Twilio calls a missing statement that mobile numbers collected for texting will not be shared or sold to third parties or lead generators "a major source of 10DLC rejection."
• Weak opt-in description: the reviewer needs to see where consent happens (a web form, a paper intake form, a keyword), what it says, and that any consent checkbox is unchecked by default.
• Missing disclosures in the call to action: program name, message frequency for recurring programs, "Message and data rates may apply," links to terms and privacy policy, and opt-out instructions such as "Reply STOP to cancel."
• Vague campaign descriptions: Twilio gives "This campaign sends messages to customers" as an example that was rejected. Say who sends, who receives and why.
• Verbal consent for marketing: Twilio's guide states that verbal consent is not sufficient for marketing use cases.

Start with registration status, then work toward the content of the messages. Most texting tools show delivery status per message, and the error code tells you which problem you have.

• Look up the error code on failed messages. A code for an unregistered number points to registration; a filtering code points to content or consent.
• Confirm the brand and campaign both show as approved, not pending or failed.
• Confirm every number you send from is attached to the approved campaign. New numbers added for a second location are a common miss.
• Compare what you are sending with what you registered. A campaign approved for appointment reminders does not cover promotional offers.
• Remove public link shorteners and use links on your own domain.
• Check that STOP, HELP and opt-out handling still work in your platform, and that people who opted out are not being re-added by an import.

Plan for weeks, not days. Twilio's 2023 announcement warned that campaign approvals could take two to three weeks because of registration volume, and a rejected campaign restarts the wait after you fix it. Register before you launch a new reminder flow, switch phone providers or open a new location, not after customers stop getting messages.

Getting the first submission right is the fastest path. Publish the privacy policy language, build the opt-in form with its disclosures, and write sample messages that match what you will actually send. A med spa that writes its reminder and rebooking texts before registering, and registers them as a mixed campaign, avoids a second round when marketing texts start.

One person should own it, even if a vendor submits the forms. That person keeps the registration details current (address changes, new numbers, new message types), knows where consent is captured, and reviews new message templates before they go live. Registration also sits alongside the consent rules for business texting, which are a separate question from carrier approval; our guide on texting customers and consent rules covers that side.

Monvell's Communications and Platform teams set up texting for reminders, follow-up and missed-call recovery with the registration, opt-in language and number assignment handled as part of the build, so messages arrive from the start.