IBM 5280 User's Setup Procedures page 148

142
6. You have the 1200 BPS integrated switched COT or CBS type
communications line. Do the following:
a. Push the connector into the receiving connector and turn the
thumbscrews until tight.
From a 5288 or 5285
CDT Type Data Coupler
(It is probably located on
a wall or by a telephone.)
~
White/Black Wire
To /.
(DT)
Thumbscrews Ii ( OR
Coupler
Terminal
SH
SG
DA
CCT
OH
RI
DT
DR
Connector
Wire
Color
Red
Gray
Yellow
Brown
Blue
Violet
White
Black
Receiving
Connector
Note: The data coupler (two or eight wires) should have been connected
prior to setup. If it has not been, contact your supervisor who will notify
the person familiar with the local electrical codes and responsible for
telephone line connection.
b. Notify your supervisor that you have completed setup.