What is SMPP?

Short Message Peer-to-Peer (SMPP) is a protocol used to exchange short messages between two entities over a packet-switched network. It is used primarily for mobile messaging applications, such as text messaging, but can also be used for other applications, such as WAP push. 

SMPP is an open-standard protocol, which makes it ideal for use in different types of environments.

How does it work?

SMPP works by allowing two entities, such as a mobile operator and an application provider, to connect to each other via a packet-switched network. The protocol enables them to exchange short messages in both directions, using the same session. 

The protocol provides a set of commands for each entity to send to the other, which are then processed and responded to accordingly. SMPP also provides for reliable message delivery, using various techniques such as acknowledgments and retries.

SMPP is often used to allow third parties to submit bulk messages but may be also used for SMS peering. Because of its versatility and support for non-GSM SMS protocols, this is the most commonly used protocol for short message exchange outside SS7 networks.