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Installing the main distribution frame
16 Installing and Connecting the MDF and Telephones
Main distribution frame cross-connect fields
Each main distribution frame (MDF) contains a trunk/auxiliary field and a distribution field. The
trunk/auxiliary field contains three cross-connect areas:
● The green field terminates the network interface leads from the central office (CO) and
provides the terminals to cross-connect the leads to the purple or yellow fields as required.
A single row of the 110-type terminal block can terminate 24 1-pair, 8 3-pair, or 12 2-pair
trunks.
● The purple field terminates the trunk circuits from the media gateway with WP-90929, List
1 or 3 concentrator cables. Also, 25-pair cables can be used to terminate trunk circuits
from the media gateway with each trunk circuit pack connecting to one 25-pair row of the
110-type terminal block. Each terminal block row can terminate 24 1-pair, 8 3-pair, or 12
2-pair trunks.
● The yellow field provides cross-connect terminals for all miscellaneous leads from the
media gateway, such as alarm monitors, emergency transfer relay power, and attendant
console power. This field is used for emergency transfer wiring, paging equipment, music
sources, and so forth.
The distribution field contains four cross-connect areas:
● The purple field (port field) terminates 25-pair cables from the media gateway. Each line
circuit pack connects to one 25-pair row of the 110-type terminal block. One 25-pair cable
is required for each line circuit pack.
Note:
Note: The TN2183 16-port Analog Line circuit pack requires an adapter cable to
connect from one connector on the media gateway to two 25-pair connectors on
a terminal block. The yellow field (auxiliary field) terminates all 25-pair cables
from the auxiliary cabinet (if used). The yellow field is located in the lower
right-hand corner of the distribution field.
● The white field (station field) terminates the station wiring. The white field indicates 3-pair
station circuits (eight circuits per 25-pair cable) routed through a satellite closet.
● The blue field (station field) also terminates station wiring. The blue field indicates 3- and/
or 4-pair station circuits (eight or six circuits, respectively, per 25-pair cable). The fourth
pair, of the 4-pair station circuit provides adjunct power from the cross-connect field on an
as-needed basis to telephones and consoles within 250 feet (76 meters) of the MDF.