A2P (application-to-person)

A2P refers to messages (mostly SMS) sent by an application on behalf of a business to a customer's phone, as opposed to P2P (person-to-person), exchanged between two people from an ordinary handset. Carriers treat the two flows differently: A2P traffic is identified, billed, filtered and — in most countries — subject to prior registration with carriers or dedicated registries (10DLC in the US, for example).

For a local business, nearly everything you send automatically is A2P: appointment confirmations, visit reminders, a text-back after a missed call. Ignoring that status has a direct consequence: unregistered traffic is increasingly blocked or flagged as spam by carriers. Going through a serious provider that handles registration and consent spares you from discovering one morning that none of your texts are being delivered anymore.