A computer system that converts one messaging protocol to another. It provides an interface between two store and forward nodes, or message transfer agents (MTAs).

Sending short (wireless data) messages to a smart phone, pager, wireless PDA or other handheld device via the Internet. Text-messaging implies sending short messages generally no more than a couple of hundred characters in length. In Europe, text-messaging was popularized by the GSM cell phone system's Short Messaging Service (SMS), which supports messages of up to 160 characters.