Casio MPC-501 - Manual (Page 119)

119
3
MBH7MD23-8556CA
communication connector
Connecting to telephone line
The dedicated modular cable that comes with the modem shall be
used to connect the modem to the telephone line.
In this case, if the telephone line is available through the modular
jack, it is possible to connect the modem to the telephone line with
the dedicated communication cable directly.
Otherwise, an adapter is required or modification of the telephone
line socket might be necessary.