What is A2P SMS?
A2P (application-to-person) SMS is software messaging people — OTPs, alerts, notifications, marketing. It is billed, routed, and regulated completely differently from person-to-person texting.
Definition
A2P — application-to-person — SMS is any message sent by software to a human: one-time passwords, delivery notifications, appointment reminders, fraud alerts, marketing campaigns. It is the commercial half of SMS, distinguished from P2P (person-to-person) traffic exchanged between subscribers. The distinction is not cosmetic: carriers price A2P termination separately (and much higher), route it through dedicated agreements and firewalls, and regulators attach consent and sender-registration rules to it — 10DLC registration in the US, sender ID registries across Asia and Africa, GDPR-grade consent requirements in the EU.
A2P traffic reaches carriers through aggregators over SMPP or HTTP APIs, with per-network termination fees. Because official A2P rates are high, a grey market persists — traffic disguised as P2P or injected via SIM boxes to dodge fees — and carrier SMS firewalls exist largely to catch it. The A2P market is where practically all SMS revenue growth is: OTP and verification traffic alone accounts for a large share of worldwide A2P volume.
Why it matters
Every product that texts its users is an A2P sender, subject to A2P pricing and A2P rules, whether it knows it or not. Sender registration done properly, consent captured cleanly, and routes chosen deliberately are the difference between 98% OTP delivery and a support queue full of “code never arrived”.
See it in action
A2P routing and analytics for business senders →