AT&T System 75 Wiring Diagram page 178

4-PAIR
MODULAR
JACKS
(EIGHT PINS)
Figure 3-62. 258A and BR2580A Adapters
356A ADAPTER
The 356A adapter (Figure 3-63) plugs into a 25-pair female cable
connector. The 356A adapter divides the 25-pair cable into eight 3-pair
circuits. Although the circuits are 3-pair, the adapters modular jacks will
accept the 8-pin modular plug used on the 4-pair station cable. See
Adjunct Powering in Chapter 4 for details.)
Caution: Adapters wired similarly to the 356A should not be
used. Their jacks will not accept 4-pair plugs.
25-PAIR
MALE
RIBBON
CONNECTOR
BR2580A
ADAPTER
Station Wiring Design
4-PAIR
MODULAR
JACKS
(EIGHT PINS)
258A
ADAPTER
3-95