Nortel Circuit Card Installation Manual page 584

Page 584 of 906
Direct inward dial operation
Two-way, loop dial repeating, TIE trunk operation
553-3001-211 Standard 3.00
NT8D14 Universal Trunk card
Incoming calls
An incoming call from the CO places a low-resistance loop across the tip and
ring leads. See Figure 123 on
Dial pulses or DTMF tones are then presented from the CO. When the called
party answers, the universal trunk card reverses battery and ground on the tip
and ring leads to the CO. The trunk is arranged for first party release. The CO
releases the trunk by removing the low-resistance loop, at which time normal
battery and ground are restored at the near-end. This also applies to incoming
tie trunk calls from a far-end PBX.
Note: The near-end can be configured for immediate start, delay dial, or
wink start.
Incoming calls
In an incoming call configuration, the far-end initiates a call by placing a
low-resistance loop across the tip and ring leads. See Figure 125 on
and Figure 126 on page
This causes a current to flow through the battery feed resistors in the trunk
circuit. Address signaling is then applied by the far-end in the form of DTMF
tones or dial pulses. When the called party answers, an answer supervision
signal is sent by the software, causing the System to reverse battery and
ground on the tip and ringleads to the far-end. Far-end disconnect is initiated
by opening the loop while the near-end disconnect is initiated by restoring
normal battery and ground. The operation represented in Figure 125 on
page 587 and Figure 126 on
calls from a CO.
Note: Where no near-end answer supervision is provided, the party at
the far-end hangs up after recognizing near-end call termination.
August 2005
page 585 and Figure 124 on
588.
page 588 also applies to incoming DID trunk
page 586.
page 587