MEP ESPA and TAP Protocol

I know very little about these protocols:

( )Telelocator Alphanumeric Protocol (TAP) is an industry-standard protocol for sending short messages via a land-line modem to a provider of pager and/or SMS services, for onward transmission to pagers and mobile phones.[1][2]

( ) In telecommunications, a message exchange pattern (MEP) describes the pattern of messages required by a communications protocol to establish or use a communication channel. There are two major message exchange patterns — a request–response pattern, and a one-way pattern. For example, HTTP is a request–response pattern protocol, and UDP is a one-way pattern.[1]

( ESPA 4.4.4 defines a serial protocol intended for the interconnection of paging equipment with telephone exchanges or computer systems. The protocol used is message-based and is built upon the ISO1745 transport specification. The protocol is designed to support multi-drop communications on an RS485 data bus, however it is also often used point-to-point on V24/RS-232 connections. The general principle is that two equipment designed the standard should interwork satisfactorily and sanely without extensive configuration, despite the significant variations in operation of both PBX and paging systems.

But does or could FreePBX / Asterisk support these communication protocol with some additional programming?

I’m looking into hopefully reusing a device that currently interfaces with a regular PBX for sending automated SMS messages from from the PBX to pagers or mobile handsets.

If anyone has any experience of automate messaging from FreePBX / Asterisk I would be very interested and grateful for any information.

Many thanks,


Not directly with this protocol, and not directly by FreePBX or Asterisk, but using a serial port to/from a legacy PBX and an AGI script has worked for me.
If you have a specific Protocol/example then that would be trivial, If not I would line-tap that current serial connection

and then deconstruct the exact transactions for your current connection, you will need to determine

A, the actual hardware , 232/485
B, the baudrate/wordlength/handshake of the connection.

then deconstruct

C, the actual conversation


D, that’s where the fun begins :wink: