What is 10DLC? A complete guide to The Campaign Registry

10 Digit Long Code (10DLC) is the standard phone number format for text messaging in the U.S. The Campaign Registry (TCR) is the carrier-led system that requires businesses to register before sending. This guide explains what 10DLC is, how TCR works, what registration requires, and how SignalWire, a fully registered Campaign Service Provider (CSP), handles the process.

Why unregistered 10DLC messaging gets blocked, filtered, and fined

Long codes, or standard 10-digit phone numbers, were originally designed for person-to-person (P2P) messaging. As businesses began using them for A2P text campaigns, message volume increased dramatically. So did spam. U.S. carriers responded by launching The Campaign Registry for A2P 10DLC in 2020: a centralized database that links every A2P message to a verified brand and declared use case. Unregistered traffic will be filtered or blocked by carriers. And as of December 2025, newly purchased U.S. 10DLC numbers do not have messaging capabilities enabled by default. Messaging only activates after a number is assigned to an approved TCR campaign.

Why navigating The Campaign Registry without a CSP is harder than it looks

The Campaign Registry involves four categories of participants: 

1. Mobile Network Operators (MNOs) who deliver messages, 

2. Direct Connect Aggregators (DCAs) who connect to MNO gateways, 

3. Campaign Service Providers (CSPs) who register and vet campaigns, 

4. And Brands who send the messages. 

Navigating this ecosystem without a registered CSP means handling the entire process and ongoing compliance monitoring without expert guidance. Mistakes at any step cause delays, rejections, or carrier penalties.

How SignalWire simplifies The Campaign Registry

SignalWire is a fully registered Campaign Service Provider (CSP) with The Campaign Registry. That means when you register a brand and campaign through SignalWire, we handle the CSP-level vetting and push your connection request upstream to a DCA. Once accepted, your numbers are approved and your messages start delivering. SignalWire’s TCR wizard in your SignalWire dashboard walks through every required field: brand details, campaign use case, message samples, and opt-in/opt-out workflows, so registration is completed correctly the first time.

Once your brand and campaign are registered and your number is assigned, sending A2P 10DLC messages via the SignalWire API takes one REST call. The example below sends an SMS from a registered 10DLC number. The number must be assigned to an approved TCR campaign before messaging is enabled.

Send a text message using SignalWire Markup Language (SWML):

version: 1.0.0
sections:
  main:
    - send_sms:
        from_number: "+155512312345"
        to_number: "+15555554321"
        body: "Hello from SignalWire!"

version: 1.0.0
sections:
  main:
    - send_sms:
        from_number: "+155512312345"
        to_number: "+15555554321"
        body: "Hello from SignalWire!"

version: 1.0.0
sections:
  main:
    - send_sms:
        from_number: "+155512312345"
        to_number: "+15555554321"
        body: "Hello from SignalWire!"

version: 1.0.0
sections:
  main:
    - send_sms:
        from_number: "+155512312345"
        to_number: "+15555554321"
        body: "Hello from SignalWire!"

How SignalWire handles 10DLC compliance and carrier relationships

SignalWire has been a registered CSP with The Campaign Registry since TCR launched in 2020. As a CSP, SignalWire is responsible for vetting campaigns before submitting them upstream to DCAs, which means SignalWire has a direct stake in campaign quality and compliance, not just registration throughput. 10DLC throughput on SignalWire is queued and throttled automatically to carrier-approved limits based on brand vetting score and campaign use case. You do not need to manage send rate manually.