Nortel Networks Circuit Card User Manual
Page 581
NT8D14 Universal Trunk card
Page 581 of 906
Circuit Card
Description and Installation
reverse-wired trunk becomes correctly wired, the first subsequent call clears
the threshold counter and normal ground start processing is implemented.
Note 1: The far-end can reverse battery and ground upon receipt of
attendant answer.
Note 2: The near-end provides a high-impedance (>150k ohms)
disconnect signal of at least 50 ms before reconnecting the ground
detector.
Outgoing calls
For outgoing calls, the trunk provides a ground to the ring lead. The CO
responds by grounding the tip and returning dial tone. After the tip ground is
detected by the card, a low-resistance path is placed between the tip and ring
leads and the ground is removed from the ring. Addressing is then applied
from the system in the form of loop (interrupting) dial pulses or DTMF tones.
See Figure 121 on
and Figure 122 on
.
The Polarity-Sensitive/Polarity-Insensitive Packs (PSP and PIP) feature must
be set to provide for proper outgoing call-duration recording with ground start
operation. Refer to the description of loop start operation in this section for a
more complete discussion of PSP and PIP.