A2P 10DLC Explained: Sending Business Texts in the US Without Getting Filtered
If your business sends text messages to customers in the United States from a standard 10-digit phone number, there is one acronym you need to understand: A2P 10DLC. It decides whether your messages are delivered, filtered or blocked. This post explains what it is, why carriers enforce it, and what a compliant SMS campaign looks like.
This is general information, not legal advice. Check your own obligations with counsel.
What A2P 10DLC means
A2P stands for application-to-person: messages sent by software on behalf of a business, as opposed to a person texting a friend. 10DLC stands for 10-digit long code, the ordinary local phone numbers most businesses already have.
A2P 10DLC is the carrier-mandated framework for business texting over those numbers in the US. Businesses register their brand and each messaging campaign, describing who they are, what they send and how people opted in. Carriers use that registration to decide how much they trust the traffic.
Why unregistered texts get filtered
US carriers treat unregistered business traffic on 10-digit numbers as higher risk. In practice that can mean messages that are delayed, filtered or never delivered, with no error on your side that explains why. Registration does not guarantee delivery, but sending without it is the most common reason legitimate business texts go missing.
Consent comes first
Registration is only part of it. The content and consent rules sit on top, including the TCPA in the US. A compliant campaign generally needs:
- Clear opt-in. The person agreed to receive texts from you, and you can show how and when.
- Honest identification. Messages say who is sending them.
- Working opt-out. STOP ends the conversation immediately, and HELP returns contact information.
- Content that matches the registered campaign. A campaign registered for appointment reminders should not suddenly send promotions.
How Zemora handles it
Zemora AI SMS is registered for A2P 10DLC, so it is carrier-compliant from day one. On every campaign we enforce TCPA-compliant consent flows, automatic STOP and HELP handling, and per-campaign content review.
The AI side adds something a plain bulk-text tool does not: it reads replies. Positive, negative and opt-out replies are detected automatically, opt-outs are honoured on the spot, and conversations that need a person are escalated instead of answered with another template.
What about Canada?
A2P 10DLC is a US framework. Canadian messaging has its own rules, including CASL for commercial electronic messages. The same principles apply in practice: get consent, identify yourself, and make opting out easy. If you text both countries, plan for both rule sets from the start.
A quick checklist before your first campaign
- Your brand and campaign are registered for A2P 10DLC.
- You can show where and how each contact opted in.
- Every message identifies your business.
- STOP and HELP work, and opt-outs are honoured immediately.
- Messages match the use case you registered.
- Someone on your team is the named escalation point for replies the agent should not handle.
Frequently asked questions
What is A2P 10DLC?
It is the US carrier framework for application-to-person text messages sent from standard 10-digit phone numbers. Businesses register their brand and messaging campaigns so carriers can trust and deliver the traffic.
Do I need A2P 10DLC registration to text customers?
If you send business texts to US numbers from a 10-digit long code, registration is expected by the carriers. Unregistered traffic is far more likely to be filtered or blocked.
How should STOP replies be handled?
A STOP reply should end messages to that contact immediately. Zemora handles STOP and opt-out automatically on every campaign.
Is Zemora SMS available now?
Zemora AI SMS is in private beta with design partners. You can request beta access through our contact page.
Want SMS follow-up that is compliant from the first message and actually reads the replies? Request beta access.