SMPP vs HTTP SMS API: which interface should you integrate against?

HTTP SMS API. A documented HTTPS interface: your application authenticates per account and
submits messages as requests, receiving structured responses. Callbacks deliver receipts and
inbound messages to a URL you control. It is request/response, auditable in any HTTP client, and
testable from a terminal, which makes it the pragmatic choice for application integration and for
teams that want a start-to-finish answer without protocol tooling.

SMPP. Short Message Peer-to-Peer is a binary protocol designed for ESME-to-SMSC messaging.
Your application opens a persistent TCP connection, binds as a transmitter, receiver or
transceiver, and submits messages as submit_sm PDUs with delivery receipts returned as
deliver_sm. It is the interface carriers and aggregators themselves use, it is built for
sustained throughput, and it gives the client control over connection behaviour and delivery
semantics that HTTP cannot offer.