What Is A2P Messaging and Why It Matters for SMS Marketing

A2P vs P2P: The Key Difference

When you text a friend from your phone, that is P2P traffic. When a business sends a promotional message, an order confirmation, or a campaign blast through an SMS platform, that is A2P traffic. Carriers distinguish between these two types because A2P messages are sent at much higher volumes and need different infrastructure to handle.

The distinction matters because carriers apply different rules to each type. A2P messages are expected to go through registered campaigns (via 10DLC registration), use approved sending numbers, and comply with opt-in requirements. P2P messages have none of these requirements because they are assumed to be personal conversations.

Why Carriers Care About A2P Classification

Before the A2P/P2P distinction was enforced, businesses would send marketing messages through regular phone numbers at P2P rates, effectively bypassing the infrastructure and pricing designed for commercial traffic. Carriers cracked down on this because it degraded network quality, led to spam complaints, and bypassed the revenue model for commercial messaging.

Today, if you send A2P traffic through a number that is not registered for A2P use, carriers will detect the pattern and either filter your messages silently or block your number entirely. See how carrier filtering works for details on detection methods.

Types of A2P Messages

• Promotional: Marketing campaigns, sales announcements, discount codes, product launches. These require explicit opt-in consent from the recipient.
• Transactional: Order confirmations, shipping updates, appointment reminders, password resets. These are triggered by a specific user action and generally have more lenient consent requirements.
• Conversational: Two-way exchanges initiated by the business but involving back-and-forth replies. Customer support via SMS falls into this category.
• Informational: Account alerts, balance notifications, service updates. Similar to transactional but not tied to a specific transaction.

A2P Registration Requirements

In the United States, A2P messages sent through 10-digit long codes (standard phone numbers) must be registered through the 10DLC system. This involves registering your business brand with The Campaign Registry (TCR) and then registering each SMS campaign you plan to run. The registration process verifies your business identity and the type of messages you will send.

Short codes (5-6 digit numbers) and toll-free numbers have their own separate registration processes but serve the same purpose: letting carriers verify that you are a legitimate sender with appropriate consent from recipients.

Without proper registration, your messages will face heavy filtering. Carriers throttle unregistered traffic to as few as 1 message per second and actively filter messages that look like unregistered A2P content. Registered campaigns get significantly higher throughput, typically 15-75 messages per second depending on your trust score.

A2P Pricing

A2P messages cost more than P2P messages because carriers charge per-message surcharges on commercial traffic. These surcharges vary by carrier and message type. As of 2024, the major US carriers charge between $0.003 and $0.005 per message segment for registered A2P traffic, on top of the base sending cost from your SMS provider.

Unregistered A2P traffic that manages to get through costs even more because providers charge higher rates for unregistered sending, and the deliverability is poor enough that you end up paying for messages that never arrive. Registration is both cheaper and more reliable. See SMS cost breakdown for full pricing details.

How the Platform Handles A2P

The platform sends all SMS traffic as properly registered A2P messages through carrier-approved routes. When you set up your sending number, the platform handles the 10DLC registration process and routes your messages through compliant pathways. This means your messages are properly identified as commercial traffic, receive the throughput benefits of registration, and avoid the filtering that hits unregistered senders.

The platform also handles message encoding, segment splitting, and carrier-specific formatting automatically, so you do not need to worry about the technical details of A2P delivery. You write your message, select your audience, and the platform handles the rest.