SMPP (Short Message Peer-to-Peer)

The SMPP (Short Message Peer-to-Peer) protocol is an open, industry standard protocol designed to provide a flexible data communications interface for the transfer of short message data between External Short Message Entities (ESME), Routing Entities (RE) and Message Centres (MC). It is a means by which applications can send SMS messages to mobile devices and receive SMS from mobile devices. This is done using an SMPP connection with a Short Message Service Center (SMSC), SMS gateway, SMPP gateway or hub. See SMPP Protocol [smpp.org] and SMPP v5 reference section.

Melrose Labs SMPP SMS Gateway
Melrose Labs SMSC Simulator
Melrose Labs SMPP Testing