A2P SMS refers to messages sent from a software application to a mobile userโs handset. Unlike P2P (person-to-person) SMS, A2P traffic originates from a business system โ automated alerts, OTP codes, appointment reminders, marketing campaigns โ and is delivered via carrier-grade messaging gateways. A2P SMS is the dominant commercial SMS model globally, governed by carrier registration programmes such as 10DLC in the US and equivalent frameworks in other markets.
A2P (Application-to-Person) SMS is sent from a software application or business system to a mobile user โ think OTP codes, appointment reminders, or marketing messages. P2P (Person-to-Person) SMS is a standard text exchange between two individuals. The key difference is origin: A2P traffic comes from automated platforms and is subject to carrier registration requirements such as 10DLC in the US, while P2P traffic is treated as conversational and governed by consumer messaging rules.
Bulk SMS is a type of A2P SMS, but not all A2P SMS is bulk SMS. A2P covers any application-originated message โ including single transactional messages like OTPs or delivery notifications. Bulk SMS specifically refers to high-volume broadcast campaigns sent to large recipient lists simultaneously. Both fall under the A2P umbrella and require the same carrier registration (such as 10DLC) to achieve reliable deliverability.
In the US, businesses sending A2P SMS via 10-digit long codes (10DLC) must register their brand and each messaging campaign with The Campaign Registry (TCR). Registration requires submitting your business details (EIN, company name, vertical) and describing the specific use case for each campaign (e.g. marketing, OTP, customer care). Approved campaigns receive higher throughput limits and significantly lower carrier filtering rates. Toll-free numbers require separate toll-free verification, and short codes require their own carrier application process.
A2P SMS pricing is typically charged per message segment (one segment = up to 160 characters for standard SMS, or 153 characters for multi-part messages). Pricing varies by country, route quality, and volume. In the US, carriers also charge a 10DLC surcharge per message on registered long code traffic โ currently a few tenths of a cent per message โ passed through by messaging providers. Wholesale A2P rates are significantly lower than retail CPaaS rates for high-volume senders.
