What is A2P messaging?

A2P messaging stands for application-to-person messaging. It's text messaging originated by a business's software system and sent to a consumer's phone — not a text from one human to another. When you get an appointment reminder from your dentist, a verification code from your bank, or a shipping update from Amazon, that's A2P messaging.

A2P is the counterpart to P2P messaging (person-to-person) — the text messages two humans send each other. Mobile carriers treat A2P and P2P very differently, with A2P subject to registration, rate limits, and content review that P2P traffic isn't.

What counts as A2P

• Appointment reminders ("Your appointment is tomorrow at 10am")

• Order and delivery updates ("Your package is out for delivery")

• Two-factor authentication codes

• Account notifications ("Your payment was declined")

• Marketing promotions

• Customer support (even two-way conversational support, if the business side is software-powered)

• Survey and feedback requests

• AI agent follow-ups (like those sent by 365agents after a phone call)

Why carriers care

A2P traffic is where SMS spam and scams live. By requiring A2P senders to register, carriers can:

• Filter out unregistered messages before they reach consumer phones

• Assign throughput limits that prevent any one sender from flooding

• Tie every message back to a real business and a specific use case

• Respond to consumer complaints by throttling or revoking specific senders

• Apply fees that fund the registration and filtering infrastructure

The A2P registration process in the U.S.

• Register your brand (your business identity) with The Campaign Registry (TCR)

• Register each campaign (each distinct use case you'll send messages for)

• Receive a campaign-specific throughput allowance once approved

• Pay per-campaign and per-message carrier fees

• Keep your registration accurate as your business or use cases change

The path is 10DLC for most businesses, short codes for very high volumes, or toll-free messaging for toll-free numbers.

Consent requirements

A2P messaging is subject to the TCPA and related consent rules. You can't send commercial messages to someone who hasn't opted in. The required form of consent varies by message type:

• Transactional (order updates, appointment reminders, 2FA) — implied consent from the existing relationship is usually acceptable, though explicit opt-in is stronger

• Informational — requires affirmative opt-in

• Marketing — requires prior express written consent, which is the strictest standard

See our Text messaging compliance collection for the specific rules and how we help you stay compliant.

Common mistakes businesses make

• Assuming they can text any customer who has shared their phone number (no — you need consent for the specific messaging use case)

• Using a personal cell phone to send business texts (not A2P-compliant, and P2P traffic patterns can get the number flagged)

• Skipping campaign registration because "it's just a few messages" (unregistered traffic gets filtered)

• Forgetting to honor opt-outs (STOP, UNSUBSCRIBE, CANCEL all trigger required opt-out handling)

• Mixing use cases on a single campaign (each distinct use case needs its own campaign registration)

Related concepts

• 10DLC — the dominant A2P path in the U.S.

• The TCPA — consent law governing when A2P is allowed

• Text messaging compliance help collection

See it in action

The Receptionist Agent at 365agents sends A2P messages to your callers — appointment confirmations, follow-up summaries, booking links — from your registered 10DLC number. We handle the registration, consent capture, opt-out handling, and carrier compliance so you don't have to become an A2P expert.