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What 10DLC is, and why AgentMessage needs you to register

About a 3-minute read.

The short version

If your application sends text messages to US phone numbers from a regular 10-digit number, the major wireless carriers require it to be registered first. That registration is called 10DLC, "10-digit long code."

This isn't an AgentMessage rule. The carriers (AT&T, T-Mobile, Verizon) block unregistered business traffic at the network level. Since February 2025, unregistered application-to-person texts are blocked across all US carriers. No registration, no delivery, and no error your recipient ever sees.

So before your agent can text anyone, two things have to be registered:

  1. A brand, the business the messages come from (legal name, EIN, address, website).
  2. One or more campaigns, a description of what the agent will text about (appointment confirmations, login codes, order updates, and so on).

Once both are approved, you attach phone numbers to the campaign and start sending. AgentMessage handles the filing with the registry; you provide the information.

Why it exists

Before 10DLC, a business sending volume from an ordinary number had no approved path on the carrier networks, and carriers had no way to tell a legitimate appointment reminder from a spam blast. The industry's fix was a registry: every business sender registers who they are (the brand) and what they send (the campaign), and that record travels with their traffic.

For an agent builder, the practical upshot is simple: the carriers want to know there's a real, identifiable business behind the messages your agent sends, and that the people receiving them asked to.

What 10DLC covers

  • SMS and MMS, text and picture messages.
  • Group messages, one registration covers one-to-one and group threads.
  • US recipients. Canada-to-Canada traffic doesn't need 10DLC, but anything reaching a US carrier network does.

What it doesn't cover

  • Short codes (5-6 digit numbers), a separate program.
  • Toll-free numbers (1-800, 1-888), their own verification process. (Toll-free SMS is on the AgentMessage roadmap.)
  • iMessage, AgentMessage offers iMessage separately; it isn't 10DLC.
  • Genuine person-to-person texting between two people having a real conversation.

What you'll actually do in AgentMessage

Three steps, in order:

  1. Register your brand, your business identity. You fill out a form; AgentMessage files it with the registry. Often verified within minutes.
  2. Register your campaign, what your agent sends and how people opt in. Approval ranges from minutes to a few weeks depending on the use case.
  3. Attach phone numbers, connect your AgentMessage numbers to the approved campaign. Minutes.

Each step has its own guide. Start with Gather these before you start so you don't get halfway in and stall.

What happens if you skip it

You can't send. The carriers drop unregistered business traffic before it reaches the handset. There's no workaround and no warning, the messages just don't arrive.

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