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Technician’s Handbook
72
Test/Verify (Loop Start)
Verify far-end (CO) circuits by using a standard telephone set in place
of the Loop Start trunk circuit.
Verify near-end (PBX Loop Start) circuits by connecting to a local PBX
ONS circuit.
Check for appropriate voltages on Tip-Ring in each call state.
During off-hook condition, 18 mA DC minimum should be drawn from
the CO (typical 25-40 mA).
Some Key/PBX systems may be polarity sensitive; reverse Tip-Ring to
verify.
Receipt of Digits
Audible Tones - Busy,
Reorder, Ringback dependent
upon digits dialed and called
party condition
-
Answer Supervision Some COs can reverse
current flow
Tip-Ring leads activated
(shorted); Loop Current
flows in line
Disconnect
Supervision
Near- end termination:
PBX/Telephone can break
Loop Current
Near- end termination:
PBX/Telephone can
break Loop Current
Table 6: Loop Start Line/Trunk Summary (Continued)
Signal
Loop Start Line PBX
Outgoing
Loop Start Line PBX
Incoming
(Sheet 2 of 2)
Содержание SX-200 EL
Страница 1: ...TECHNICIAN S HANDBOOK LIGHTWARE 19 RELEASE 3 0 ...
Страница 11: ...Chapter 1 Introduction ...
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Страница 32: ...Technician s Handbook 22 ...
Страница 33: ...Chapter 2 Routine Maintenance ...
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Страница 55: ...Chapter 3 Troubleshooting and Repair ...
Страница 56: ...Technician s Handbook 46 ...
Страница 88: ...Technician s Handbook 78 Figure 16 E M Trunk Type I 2 wire ...
Страница 110: ...Technician s Handbook 100 ...
Страница 111: ...Chapter 4 Programming ...
Страница 112: ......
Страница 168: ...Technician s Handbook 158 ...
Страница 169: ...Chapter 5 Installation ...
Страница 170: ......
Страница 175: ...Installation 165 Installation SX 200 ML FD Cabinet Card Assignment Figure 24 SX 200 ML FD Cabinet Card Assignment ...
Страница 176: ...Technician s Handbook 166 SX 200 LIGHT Cabinet Card Assignment Figure 25 SX 200 LIGHT Cabinet Card Assignment ...
Страница 239: ...Chapter 6 Maintenance Commands ...
Страница 240: ......
Страница 258: ...Technician s Handbook 248 ...
Страница 261: ...Notes ...
Страница 262: ...Technician s Handbook Notes ...