SNPP (Simple Network Paging Protocol)
Simple Network Paging Protocol (SNPP) is a protocol that defines a method by which a pager can receive or send (in some cases) a message over the Internet. It is supported by most major paging providers, and serves as an alternative to the paging modems used by many telecommunications services.
SNPP was initially developed as a one-way solution, but it has evolved into a protocol capable of supporting two-way messaging. It is a fairly simple protocol that can run over TCP/IP and send out a page using only a handful of well-documented commands.
Messages are sent from a computer to the paging or cellular carrier via the Internet. The carrier then passes the message to the paging terminal. The paging terminal then broadcasts the message via radio waves to the paging device, mobile phone, billboards, or other designated wireless device. Maximum message length can be carrier-dependent.
Once connected, a user can simply enter the commands to send a message to a pager connected to that network. For example, issue the PAGE command with the number of the device to send the message to. Next, issue the MESS command with the text of the message. Then issue the SEND command to send out the message to the pager, and then QUIT, or send another message to a different device.
The protocol allows the user to issue multiple PAGE commands per message, allowing the same message to be sent to several devices on that network with one MESS and SEND command pair.