Nortel Networks Circuit Card 311 - Manual (Page 588)

588 NT8D14 Universal Trunk card
Figure 148
Loop start call connection sequence - incoming call from CO/FX/WATS
The alerting signal is 20 Hz ringing sent by North American CO. When an
incoming call is answered, ringing is tripped when the trunk places a low
resistance DC loop towards the CO.
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 01.04 Standard
Release 5.0 23 May 2008
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