Is US A2P 10DLC Registration Required? Yes — Here’s Why

If you are asking whether US A2P 10DLC registration is required, the short answer is yes — for any business sending application-to-person messages to US phone numbers from a 10-digit long code. There is no volume threshold and no geographic exemption.

Blocked, not filtered

The important change is what "unregistered" now means. Carriers used to filter a portion of unregistered traffic — some got through, which made the problem easy to ignore. That era is over. Unregistered A2P traffic is now blocked at the network.

Fig 1 — The gap between unregistered and registered delivery is close to total.

This is why the failure mode is so distinctive. A content or reputation problem degrades delivery gradually. A registration gap makes messages stop arriving entirely. If your texts went from working to nothing, registration is the first and most likely cause.

It applies wherever you are based

US A2P 10DLC governs messages delivered to US numbers, not the location of the sender. A business in London or Toronto texting American customers needs to register exactly as much as one in Ohio. The recipient's number is what triggers the rule.

What to do about it

• Register your brand and campaign before sending another message.
• If you send through a platform, its console files on your behalf — but the requirement is yours, not theirs.
• Diary your renewal: registrations are renewed annually, and an expired one puts you straight back into blocked traffic.