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6-4
PORT TYPES/INSTALLATION COMPATIBILITIES
Although the D4-channel bank is compatible with other devices using D4 standards, its most frequent
application (from this document’s perspective) is as the interface between a DIMENSION
®
and DS1
or T1 facilities. The physical connections from the D4 to the switch are identical to connections used
in any 4-wire analog tie trunk connection. The 4-wire E&M-ER tie trunk should be used because
these units include variable attenuators in the range between 0 and 25.5 dB. Therefore, external
attenuator pads are not required. Since both analog and digital tie trunks are involved in the end-to-
end link, the end-to-end transmission facilities (called a combination tie trunk).
GENERIC 1 DS1/DMI-BOS
The operating mode and supported port types for Generic 1 DS1/DMI-BOS are described next.
Operating Mode
Except for the spare slot adjacent to the pack, there are no special slot or option strap considerations
for Generic 1 DS1/DMI, as with Generic 2. The TN722, TN722B, and TN767 plug into any normal
port slot in the system.
Supported Port Types
The TN722 and TN722B only emulate tie-trunk signaling. That is, they provide 2-state signaling
(on-hook/off-hook signaling). Two categories of trunk types perform 2-state signaling: tie trunks
and DMI trunks.
The TN767 circuit pack provides CO in addition to tie and DMI trunk types. That is, it provides 4-
state signaling (on-hook/off-hook signaling as well as ringing and no-ringing indication, and reverse
battery).
NOTE: No restrictions are placed on the type of framing, signaling, or line-coding options used
with any of the port types. However, take care to assure that the interface options are
compatible with the distant endpoint (D4-channel banks are not now compatible with 24th-
channel signaling; most D4-channel banks do not support ESF framing).
Tie Trunk
Generic 1 DS1/DMI tie trunks appear to the switch software as a TN760B analog tie trunk.
Therefore, things that can be administered for a digital tie trunk can also be administered for an
analog tie trunk (except for alternate voice/data (AVD) common-type trunks).
A tie trunk port presents an interface of a channel unit requiring tie trunk signaling to a far end D4-
channel bank. Since six types of tie-trunk channel units use the same digital signaling format, there
may not be a one-to-one relationship between a DS1/DMI tie-trunk port and the channel unit on
which it terminates at a channel bank. The six types of channel units are type I, II, and III 4-wire
E&M, and type I, II, and III 2-wire E&M. While these channel units have the same digital