OpenSMPP is an open source Java library which implements the SMPP (Short Message Peer to Peer) protocol. It is based on an open source Java SMPP API originally released by Logica. It can be used to develop ESMEs (External Short Message Entities), Messaging Gateways, and more.

Also provided are some basic command line based tools to simulate an ESME or SMSC for testing of SMPP applications. They also serve as examples of how to use the API.

At the moment only SMPP version 3.4 is supported. However, there are plans to introduce support for SMPP version 5.0. Details can be seen in the roadmap.

Support used to be provided via the forums at SMS Forum; but since SMS Forum ceased operations at the end of 2007, official support is no longer available.