Nortel Networks 1000 - Manual (Page 521)

Operation 521
Trunks identified as possibly reverse wired are switched by software to
loop start processing after the second ring. This switching takes place on a
call-by-call basis. So if a previously correctly wired trunk becomes reverse
wired, the next incoming call is marked as possibly reverse wired and the
threshold count begins.
If the threshold count exceeds its limit, an error message is printed and
the trunk is registered as "positively reverse wired." When identified
as positively reverse wired, the call is presented continuously from the
first ring. When a reverse-wired trunk becomes correctly wired, the first
subsequent call clears the threshold counter and normal ground start
processing is implemented.
The CS 1000 software includes a feature for detecting reverse wiring
(connection of the near-end tip and ring leads to the far-end ring and tip
leads) on ground start trunks with far-end answer supervision.
Ordinarily, an incoming call on a reverse-wired trunk without reverse-wiring
compensation presents ringing on the tip lead rather than on the ring lead.
Since the software expects to see a ground on the tip lead, it interprets
the end of the first ringing signal as a switchhook flash. But since the
interval between ringing signals exceeds the switchhook flash time of 512
milliseconds, the software assumes a far-end disconnect. This causes the
call to be presented to a console loop key and then immediately removed.
The reverse-wiring compensation feature operates as follows. If an
apparent disconnect takes place immediately after the first ringing signal,
the software time stamps the event and temporarily remove the call from
the console loop key. If another such ringing/disconnect event occurs
during the No Ringing Detector (NRD) time, the trunk is considered
"possibly reverse-wired" and a threshold counter starts. Calls on trunks
identified as possibly reverse-wired are presented to the attendant during
the initial ring, removed, and then continuously presented after the second
ring. If a call on a possibly reverse-wired trunk is abandoned before the
attendant answers, it is disconnected after the NRD timer expires.
A trunk identified as possibly reverse-wired is switched by the software
to loop start processing after the second ring. This switching takes place
on a call-by-call basis. So if a previously correctly wired trunk becomes
reverse-wired, the next incoming call is marked as possibly reverse-wired
and the threshold count begins.
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 02.06 Standard
27 August 2008
Copyright © 2003-2008 Nortel Networks
.