Specifications

Trunk Cards and Connections
72 025-9035AA
TELCO Connectors
A 66 type punch-down block (Zetron part number 802-0093 or equivalent) is
recommended for connecting the backplane RJ21 50 pin connectors to telephone company
supplied registered jacks.
For End-to-End loop start, End-to-End ground start, or DID trunks, cross connect only the
RING/TIP pair from the Zetron terminal to the telephone company installed jacks. This is
usually one or two RJ21 type jacks supplied by the telephone company.
For PABX E&M trunks, cross connect the RING/TIP and E/M pairs or directly terminate
the RJ2EX jack of the Zetron terminal to the telephone company installed RJ21 registered
jacks. This is usually three or four RJ21 type jacks supplied by the telephone company.
See Figure 9 on page 38. Primary and secondary protection is recommended using Zetron
protection kit (Zetron part number 950-9040).
The following charts detail the pinout for the telephone RJ21 connectors. Wire colors are
shown for standard 25-pair telephone cabling.