Message Exchange & PDUs

In SMPP, Protocol Data Units (PDUs) are the fundamental communication packets used to exchange information between an ESME and an SMSC. PDUs carry commands, responses, and message data to facilitate the sending, receiving, and managing of SMS messages.

PDU Structure

Each PDU in SMPP consists of two main parts: a mandatory header and an optional body.
PDU Header is a fixed-size structure of 16 octets that contains the following four mandatory parameters: