Nortel Networks 1000 User Manual

Page 681

Operation

681

Table 250
DX signaling - incoming calls with originating party release on tandem connections (cont’d.)

Condition

Current in
signaling lead

State of trunk
detector

Seizure
(Can be arranged for IS, DD, or WS) (near-end
ready for digits)

Current flow

Low

Dial CO/FX/WATS and office DN

Current flow
interrupted for each
pulse

Low-high-low for each
pulse

Stored digits outpulsed on CO/FX/WATS trunk
after ground detection if a ground start, but after
3 seconds if a loop start

If answer supervision: pseudo-answer
supervision is sent approximately 13 seconds
after last dial pulse received

No current flow

Low

If no answer supervision: CO end disconnects
(if a CO ground start – the trunk is idled and
network taken down, but the incoming TIE trunk
is held under control of the originating end)

Current flow

Low

Originating end disconnects – network taken
down and trunk idled

No current flow

High

Note:

* – CO ground start: the trunk is idled and the network taken

down, but the incoming tie trunk is controlled by the originating end.

Duplex (DX) signaling uses the voice transmission leads for signaling as
well as for voice transmission. See

“SDI function” (page 998)

For descriptive purposes, the lead pair Tip B/Ring B is designated the
signaling pair, whereas the other pair Tip A/Ring A conducts current in the
opposite direction to balance the overall current flow between the near and
far-ends. During signaling, current flows through both Tip B and Ring B
leads in the same direction.

Table 251 "DX signaling - outgoing calls with originating party release"
(page 682)

and

Table 252 "DX signaling - incoming calls with originating

party release" (page 682)

show call-connection and take-down sequencing

for DX signaling.

Table 253 "DX signaling - outgoing calls with originating

party release on tandem connections" (page 682)

and

Table 254 "DX

signaling - incoming calls with originating party release on tandem
connections" (page 683)

show sequencing where the E and M Trunk card