General information, not legal advice. A2P 10DLC is a carrier and industry registration system, not a statute, and this article describes what the published documents say as of October 2026. Registration does not answer the separate legal question of consent. Confirm your texting program with counsel. The legal side is in our guide to TCPA texting rules for contractors.
A missed-call text back is only useful if it arrives. For a contractor texting from a business number through a software platform, whether it arrives depends in part on a registration step that many shops skip because nobody told them about it. The step is called A2P 10DLC.
This guide explains what it is, who asks for it, what the registration contains, what happens to unregistered traffic and how long approval takes. Everything here comes from Twilio's documentation, The Campaign Registry and CTIA. Where a source does not give a number, we say so instead of filling the gap.
What A2P 10DLC means
The letters break down like this:
- A2P is application-to-person: messages sent by software (a CRM, a texting platform, an automation) to a person, as opposed to one person texting another from a phone.
- 10DLC is 10-digit long code: an ordinary-looking local phone number, as opposed to a toll-free number or a short code.
Twilio's documentation describes A2P 10DLC as the standard that U.S. carriers have put in place so that SMS traffic to U.S. users is verified and consensual. It says the carriers were responding to spam on person-to-person routes that were unregulated.
In other words, a local number that you use to send automated texts through a platform falls in this system. Toll-free numbers and short codes are outside it and have their own verification processes. This article covers only 10DLC.
Who requires it
Carriers do. The Campaign Registry (TCR) describes itself as the backbone support for the 10DLC messaging ecosystem: a registry where brands and the providers that send for them are verified before they can send. TCR says brands cannot register directly with it. They go through a registered Campaign Service Provider (CSP), which can be a texting platform or the communications provider underneath it.
Twilio's overview says anyone sending SMS or MMS from an application over a 10DLC number to the United States must register, and it adds that this includes individuals and hobbyists. The description turns on the sending method, not the size of the business.
Two things this is not:
- It is not a law. The rules come from carriers and the industry. CTIA's Messaging Principles and Best Practices say they do not constitute legal advice and are not a substitute for counsel.
- It is not a consent shield. Being registered tells the carriers who you are and what you send. It does not decide whether you had the right to text a given person.
The two steps: brand, then campaign
Step 1: Register the brand
The brand is your business. Twilio's guidance for Standard and Low-Volume Standard brands calls for:
- The exact legal business name as registered with your tax ID (EIN), plus legal structure and industry.
- A working website related to the business. Twilio's onboarding page says TCR rejects sites that are unreachable, parked, for sale, login-gated or that redirect elsewhere.
- An authorized representative with name, job title, phone and email. The page warns that personal or free email addresses can cause brand failure.
- A business address.
Sole Proprietor brands have a separate path. The proprietor's name serves as the brand name, and a U.S. or Canadian mobile number is required to receive a one-time passcode.
Twilio lists three brand types, and the type drives how much you can send:
| Brand type | Campaigns allowed | Daily limit to T-Mobile (SMS/MMS segments) |
|---|---|---|
| Sole Proprietor | 1 | 1,000 |
| Low-Volume Standard | up to 5 | 2,000 |
| Standard | more | 2,000 to unlimited, depending on trust score |
Those are Twilio's published figures, from its A2P 10DLC overview as of October 2026, and they apply to T-Mobile specifically. Other carriers have their own limits, which we did not verify.
Step 2: Register the campaign
A campaign describes what you send and how people agreed to get it. Twilio's requirements include:
- A description of 40 to 4,096 characters that says who sends, who receives and why.
- A message flow of 40 to 2,049 characters listing every way a person opts in.
- Two to five sample messages, each identifying your business by name or website, with square brackets around variable content.
- A use case that matches the description and the brand type.
- Accurate flags for embedded links and embedded phone numbers, with example links in the samples where possible.
- Opt-in, opt-out and help messages, if you manage those yourself.
Twilio's page says to list every opt-in method in the message flow. Whatever you write there should match what actually happens.
Privacy policy and terms URLs
Twilio's documentation says that for web opt-in, the site must have both a privacy policy and terms of service. On privacy policy content, it says the policy must be publicly accessible without a login and must include a no-sharing statement for mobile numbers, a statement of message frequency and the phrase "Message and data rates may apply." Terms must also be publicly accessible and on the same domain as the business website.
There is also a dated change. A Twilio changelog entry says that starting June 30, 2026, new A2P 10DLC campaign submissions through Twilio's Messaging REST API must include both a PrivacyPolicyUrl and a TermsAndConditionsUrl, and that both must be valid, publicly accessible URLs. Requests missing either are rejected during campaign review. The changelog says existing registered campaigns are not affected. It does not say what the policies must contain, and its wording about the exact cutoff date is inconsistent ("starting June 30" and "before June 30"), so do not rely on the edge of that date.
Practical reading: put real privacy and terms pages on your site before you submit anything, whether you use Twilio directly or a platform built on it.
What happens to unregistered traffic
On Twilio, the answer is blocking. Its changelog dated September 1, 2023 says messages sent to the U.S. from unregistered +1 10DLC numbers are blocked, return error 30034 ("US A2P 10DLC: Message from an Unregistered Number"), and that Twilio messaging rates still apply to blocked messages. Twilio's error 30034 page lists the causes:
- Your brand or campaign registration is not complete.
- The number is not in the sender pool of the messaging service linked to your approved campaign.
- You added more than one 10DLC number to a Sole Proprietor campaign, which allows one.
Its listed fixes are to finish registration, add the number to the sender pool, and for urgent sends before approval, use a non-10DLC sender such as a toll-free number or short code.
Twilio's overview also says registering "results in lower message filtering and higher messaging throughput," and that customers sending from an unregistered Twilio 10DLC number "will receive additional carrier fees."
Other websites give different start dates for carrier-level blocking, including February 2025. We could not confirm those dates against a carrier or Twilio source, so we are not repeating them. If a vendor tells you a specific enforcement date, ask for the document.
For a contractor, the consequence matters more than the date. A missed-call text back that was working can stop delivering when a number is not tied to an approved campaign, and whether your dashboard shows an error depends on your platform. If your texts are not arriving, a registration check comes before anything else. Missed calls are expensive already: the cost of a missed call is worth working out before you decide how much effort a recovery text deserves.
How long approval takes
Timelines are the part of this process most often quoted from memory, so here is what Twilio's direct standard onboarding page says, read in October 2026:
- Twilio customer profile: approval "may take 72 hours or more."
- Brand: TCR review typically happens within a few minutes after submission. A brand that lands in an in-review status goes to manual third-party review, which takes seven business days or more.
- Campaign: manual vetting can take between two and three weeks. A separate notice on the page says campaign reviews are currently taking 10 to 15 days.
Even that one page gives two campaign ranges (two to three weeks, and 10 to 15 days), and we did not find a single stated average. Treat the longest figure as the planning number, and treat all of them as moving targets. Texting cannot go out on the A2P route until the campaign is fully approved, so submit before you need it.
Twilio's onboarding checklist stresses the items that fail a brand review: the exact legal name, a website that works and relates to the business, and a business email address. Get those right before you submit.
A short readiness list
Before you submit, have these ready:
- The legal business name and EIN exactly as the IRS has them.
- A working business website at the domain you will register.
- Public privacy policy and terms pages on that domain, with the contents Twilio lists.
- A written description of how each type of person opts in: web form, inbound call, sign-up sheet, existing customer.
- Two to five sample messages that name your business.
- A business email address, not a personal one.
- A decision about who owns the registration if you change platforms. Ask your platform provider how it works.
This is also where the consent question from our TCPA guide shows up in plain sight: the message flow you write for the registration is a description of your consent process, and it should match what actually happens.
Missed-call recovery is the first component of the Booked-Jobs Recovery System, and a text sequence that does not deliver recovers no jobs, so registration belongs on the launch checklist for any lead follow-up automation.
Frequently asked questions
Do I have to register if I only text a few customers?
Twilio's overview says anyone sending SMS or MMS from an application over a 10DLC number to the U.S. must register, including individuals and hobbyists. It offers a Sole Proprietor brand type for small senders without an EIN, limited to one campaign and 1,000 segments per day to T-Mobile.
What happens if I skip registration?
On Twilio, messages from unregistered +1 10DLC numbers to the U.S. are blocked with error 30034, and standard messaging rates still apply to the blocked messages. Twilio also says unregistered senders see additional carrier fees.
How long does registration take?
Twilio's onboarding page, read in October 2026, says brand review is usually minutes but can take seven business days or more when it goes to manual review, and that campaign vetting can take two to three weeks, with reviews currently running 10 to 15 days.
Does registering mean my texts are legal?
No. Registration is a carrier requirement. Whether you had consent to text someone is a legal question under the TCPA and state law. See our guide to the TCPA rules and confirm with counsel.