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257
Basic Troubleshooting and Repair
Direct Inward Dial (DID)/Loop Trunk
You use the Direct Inward Dial (DID)/Loop trunk primarily in analog DID
applications; rarely in PBX-PBX Loop Tie trunk applications.
This trunk uses current reversal to signal supervision information and
provides digit flow capability in both directions, when the trunk is in the
loop/tie mode.
Figure 25: Direct Inward Dial (DID)/Loop Trunk