AT&T MERLIN LEGEND Release 2.0 Data User's Manual page 18

About Data Communication Equipment
Digital Voice and Analog Data. This endpoint
connects via a modem to a T/R interface supplied by a
Multi-Function Module (MFM) in an MLX telephone
which, in turn, connects to the control unit. The
modem converts the digital signal to an analog signal
that is sent through the MFM (in the MLX telephone) to
the control unit. The voice communication capabilities
of the MLX telephone and data station are completely
independent of each other.
1-8 Data Stations