Glossary
What is SMPP?
SMPP (Short Message Peer to Peer) is the protocol a system outside a mobile network uses to hand texts to an operator or aggregator message centre and collect replies and delivery receipts.
Two versions are in use. Version 3.4 was published by the SMPP Developers Forum on 12 October 1999, and version 5.0 came from the same group, renamed the SMS Forum, on 19 February 2003. Neither is a 3GPP or IETF standard. A sending system opens a connection, binds (bind_transmitter to send, bind_receiver to receive, bind_transceiver for both), then submits each text with submit_sm and receives replies and receipts as deliver_sm.
The protocol leaves a lot to the people running it. Version 3.4 suggests no more than 10 unacknowledged requests at once but lets each message centre set its own limit, and SMPP has no encryption of its own: the 5.0 specification recommends a leased line, TLS or a VPN.
Most businesses never touch SMPP directly. CaptiFi Connect takes a JSON request over HTTPS and returns a message id at once, and the network's receipt comes back to you as a delivery report and a signed webhook.
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