# What is P2A SMS?

> P2A (person-to-application) SMS is a message a mobile subscriber sends from their handset to a business application — texting a keyword like STOP, HELP, BALANCE, or a competition code to a short code or virtual long number. It is the inbound, mobile-originated counterpart to A2P (application-to-person) SMS, and the mechanism behind two-way SMS, opt-in keywords, and conversational campaigns.

- Canonical URL: https://www.broadnet.me/answers/what-is-p2a-sms
- Language: en
- Last reviewed: 2026-07-22
- Publisher: BroadNet (https://www.broadnet.me)

## P2A vs A2P — direction is everything

A2P is software sending to a handset (mobile-terminated, MT); P2A is a handset sending to software (mobile-originated, MO). P2A is billed to the consumer on their tariff, arrives at your gateway as an SMPP deliver_sm with the MO flag set, and is the technical foundation of two-way conversational SMS. See /answers/what-is-mo-vs-mt for the MO/MT distinction and /products/two-way-sms for the product.

## Where P2A shows up

Opt-out and opt-in keywords (STOP, START, HELP) that regulators require on marketing SMS; competition and voting entries; two-way customer support; and consent capture where a subscriber texts a keyword to a short code to join a programme. P2A always needs an inbound-capable number: a long number (always two-way), or a short code provisioned for MO.

## How BroadNet handles P2A

Inbound MO messages are delivered to your webhook in real time, matched to the originating conversation, and available over the same SMPP bind or REST webhook you use for A2P. Because the reply path is MO, it is priced and routed as a legitimate operator service — not a grey route. See /products/two-way-sms.

## Related

- [All answers](https://www.broadnet.me/answers)
- [Glossary](https://www.broadnet.me/answers)
- [What is A2P SMS?](https://www.broadnet.me/answers/what-is-a2p-sms)
- [MO vs MT — what's the difference?](https://www.broadnet.me/answers/what-is-mo-vs-mt)
- [Short code vs long code — when to use each](https://www.broadnet.me/answers/what-is-short-code-vs-long-code)
- [A2P vs P2P SMS — what's the difference?](https://www.broadnet.me/answers/a2p-vs-p2p-sms)
- [Two-way SMS](https://www.broadnet.me/products/two-way-sms)