A2P 10DLC ("Application-to-Person, 10-digit long code") is a US carrier framework that requires every business sending SMS from a local number to register their brand and the specific campaigns they'll run. Without it, messages get filtered, rate-limited, or blocked entirely.
When you need it
You need A2P registration if all of the following are true:
- You're sending SMS in the United States, and
- The sending number is a 10-digit local number (not toll-free), and
- The SMS is application-driven (not a human texting from a phone)
When you don't need it
- All your SMS goes from a toll-free number → do toll-free verification instead.
- You only make voice calls and never send SMS.
- You're outside the US (different countries have their own SMS regulations).
What you'll need before starting
Gather these before you open the registration form:
- Legal business name (exactly as it appears on your EIN letter)
- EIN (US tax ID)
- Business address, phone, and website
- Authorized representative name + email
- Sample SMS messages you plan to send (1–3 examples)
- Opt-in description — how do patients consent to receive texts? (e.g., "Patients enter their mobile number on our booking form and check a box agreeing to receive appointment reminders.")
How to register
- Settings → Phone Numbers → A2P 10DLC.
- Click Register brand and enter your business info.
- Click Create campaign — pick the use case (most healthcare practices choose Customer Care + Account Notifications).
- Paste your sample messages and opt-in language.
- Submit. Status will show Pending review for 1–3 business days.
You'll get an email when your brand and campaign are approved (or if they need revisions).
After approval
- Your registered local numbers will start sending SMS at full throughput.
- Daily message caps depend on your trust score (low, medium, high) — most healthcare practices land in medium (3,000 messages/day).
- You don't need to re-register existing numbers — registration is per-brand, not per-number. New numbers added to your account inherit the registration.
Common rejection reasons
- Sample messages don't include opt-out language → add "Reply STOP to unsubscribe" to every templated SMS.
- Opt-in description is vague → describe the exact form/checkbox the patient interacts with.
- EIN/business name mismatch → use the exact legal name on your IRS EIN letter.
- Website doesn't have a privacy policy mentioning SMS → add one — see our compliance & security guides.