MPC Data Protocol
From Zenitel Wiki
The AlphaCom supports a subset of the MPC data protocol used with the classic Stentofon TouchLine exchanges. As it allows control of the AlphaCom exchange by mapping MPC commands to AlphaCom commands one-to-one it can be thought of as a variant of the simple link layer, but only for single-exchange (not AlphaNet) applications.
The output is broadcast of exchange events like dialled digits, station busy/free, connection and transfers. Note that it’s possible to send additional data strings from the AlphaCom’s Event Handler on this port also.
The AlphaCom supports a subset of the MPC Data Protocol for backward compatibility. This allowed some TouchLine generation equipment like PNCI, MLH and CRM to be used with the AlphaCom.