A2P 10DLC & sender verification

Before you can send SMS campaigns to US mobile numbers, your sender has to be registered with the carriers. This page explains what that means, what they ask for, and how to complete it inside Callable.

What A2P 10DLC actually is

A2P means application-to-person — texts sent by software rather than typed by a human on a handset. That's exactly what an SMS campaign is. 10DLC means a standard 10-digit long code (a normal +1 local number).

Since 2021 the major US carriers (AT&T, T-Mobile, Verizon) require every business sending A2P traffic from a local number to register with The Campaign Registry (TCR). Callable submits that registration for you through Telnyx.

• If you don't register: carriers silently filter or throttle your messages. They're accepted by the API and simply never arrive — which looks like "SMS is broken" rather than a compliance problem.
• If you do register: you get real throughput and deliverability, with limits based on a trust score derived from your business details.

This is a carrier requirement, not a Callable one. No setting or workaround removes it.

Two routes: toll-free or 10DLC

You pick one sender identity.

Toll-free verification — recommended to start

• No TCR brand: a single carrier review
• One form to fill in
• Review typically takes a few days
• No registration fee
• Best for getting live quickly and for lower volume

A2P 10DLC

• Registers a brand and a campaign with The Campaign Registry
• Two steps: brand first, then the campaign
• Brand vetting is often minutes to hours; campaign review 1–3 days
• Roughly $4 one-time brand + $15 campaign vetting + $1.50–10/month
• Best for high volume — the best throughput and lowest cost per message

Toll-free is the recommended default: one review, no brand to build. Move to 10DLC when your volume justifies it.

What the carriers ask for

Business identity (both routes)

• Legal business name, exactly as registered
• Website (must be live and match the business)
• Contact name, email, and phone
• 10DLC additionally needs your EIN / tax ID, entity type, and registered address

About the messages (both routes)

• What you'll send and why (use case + description)
• Sample messages — real examples of the actual texts
• Opt-in workflow — how recipients agreed to be texted, usually a form URL or a screenshot of the consent checkbox
• Honoring STOP and HELP — Callable does this automatically

The opt-in requirement, plainly

Every route — toll-free and 10DLC — requires you to document how recipients consented. This is the item carriers scrutinize most, and it has a real consequence:

So a campaign built on a purchased list of strangers generally cannot pass verification, and shouldn't be attempted. What does pass:

• Warm lists — customers, form fills, and anyone who gave you their number with consent. This is the compliant path and it verifies cleanly.
• Toll-free for lower-volume mixed use.
• Non-US markets, which have their own rules (no 10DLC, but country-specific sender-ID regimes).

Verify your sender in Callable

Go to Numbers → SMS sender verification.

1. Choose Toll-free (recommended) or A2P 10DLC.
2. Fill in your business details, sample messages, and opt-in workflow.
3. Submit. For 10DLC you'll register the brand first, then describe the campaign.
4. The card shows live status — Under review → Verified. If a carrier declines, the reason is shown so you can fix it and resubmit.

The card refreshes itself; you can also hit Refresh status.

The launch gate

An SMS campaign can't launch until your sender is verified. If you try, you'll see a "Verify your SMS sender first" banner linking straight to the verification card.

This is deliberate. Without it, an unverified campaign appears to send perfectly while carriers quietly discard the messages — you'd pay for traffic that never arrives and have no signal that anything was wrong.

Next steps

• Cold SMS & inbox — running campaigns, the two-way inbox, rate and volume caps
• Phone numbers — buying the number you'll send from