Technical information

Technician’s Handbook
78
Table 8: Direct Inward Dial/Loop Trunk Summary
Signal
DID/Loop Trunk PBX
Outgoing
DID/Loop Trunk PBX
Incoming
Seize
Tip-Ring leads are acti-
vated (shorted); Loop Cur-
rent flows in line
Tip-Ring leads are acti-
vated (shorted); Loop
Current flows in line
Seize
Acknowledgment
Immediate Dial - Tip-Ring
leads stay active
Outgoing Wink - Tip-Ring
leads toggle
Loop Current direction
Delay Dial - Tip-Ring leads
reverse Loop Current fol-
lowing seizure; reverse
again when ready to go
Immediate Dial -
Tip-Ring leads stay
active.
Incoming Wink -
Tip-Ring leads toggle
Loop Current direction
Digits
Loop Current toggled
(Rotary) or DTMF
Loop Current toggled
(Rotary) or DTMF
Stop Dial
Tip-Ring leads reverse
Loop Current direction; for-
ward again when ready
-
Receipt of Digits
Audible Tones - Busy,
Reorder, Ringback depen-
dent upon digits dialed and
called party condition
Audible Tones - Busy,
Reorder, Ringback gen-
erated and sent to call-
ing party dependent
upon digits received
and state of called party
Answer
Supervision
Current flow in Tip-Ring is
reversed
Current flow in Tip-Ring
is reversed
Disconnect
Supervision
Near or Far-end termina-
tion: Loop Current broken
Near or Far-end termi-
nation: Loop Current is
broken