What is A2P SMS? Business messaging

Two kinds, one network

A bank sends a login code. A courier sends a delivery window. A retailer sends an opted-in offer. Each message starts in an application, so each is A2P: application-to-person. A person texting a friend is P2P: person-to-person. The handset, the radio network and often the same message center carry both. The difference is who starts the message and what the network knows about the sender.

That difference changes the treatment. A2P traffic runs on a registered sender and a business route. P2P runs on a consumer subscription. The same words can be A2P from a bank and P2P from a friend, and the network should treat them differently.

The receipt is a network status

A delivery receipt, or DLR, reports what the network did with a submitted message. It may say delivered, expired, undelivered or unknown, with a code that explains the state. It does not say that a person opened the message, read the code or acted on it. A handset that is off, full or out of coverage produces a different state from a handset that received the message and ignored it.

Read the DLR as one signal in the funnel. Pair it with your own events: code entered, order completed, reply received. A high delivery rate with a low completion rate points to the message, the sender or the form, not to the network alone.

Three traffic types, three sets of rules

Authentication traffic carries one-time passwords, login approvals and verification codes. It is small, time-sensitive and valuable to an attacker. Transactional traffic carries alerts, receipts and appointment reminders. Promotional traffic carries marketing and re-engagement messages, and it needs a recorded opt-in and a working opt-out.

Keep the three apart. A marketing burst on the same route can delay a login code. An authentication route sized for short codes may not match a campaign that needs a high sustained rate. Each type also meets its own content filters, so a template that passes for one can fail for another.

What buyers check

Ask which sender types work in each destination and what registration each needs. Ask which routes carry your traffic and whether the provider tells you before a route changes. Ask what a delivery receipt means and whether the provider tests handsets in the markets you care about. Ask how content is screened and how opt-outs are handled.

Ask for a test route with your own content and sender before launch. Ask what data the provider keeps and for how long. Ask what happens when a route fails or a sender is rejected. Ask who tells you when a route changes and how much notice you get. The SMPP explainer covers the connection; the sender ID guide covers registration in Mexico and Brazil.

Put the answers in one table: destination, sender type, registration owner, route, test date and fallback. A table with gaps is more useful than a polished deck, because it shows which question the provider did not answer. Score the evidence, not the relationship.

P2P, P2A and two-way

A2P describes the outbound direction: application to person. P2A describes the reverse: a person replies to the application, and the reply reaches a callback or an inbox. A two-way program uses both. The reply path needs a sender that can receive messages, usually a short code or a long number, and a route that carries mobile-originated traffic. An alphanumeric sender usually cannot receive replies, which is why two-way programs choose a number.

P2P remains person-to-person and is not a business channel. A business that asks customers to text a personal number creates a P2P flow with business consequences: no sender registration, no delivery report to the business and no control over the route. If the program needs accountability, use an A2P sender with a two-way path.