Instruction manual

FUNCTIONAL DESCRIPTION
Tip Ring Line (ZTN78)
The Tip Ring Line Circuit Pack interfaces eight analog tip and ring voice terminal lines
(single-line voice terminals) and the TDM bus.
Figure 3-17 shows the Tip and Ring Line
unique circuitry.
The TN742 can be used instead of the ZTN78 Tip Ring CP. The TN742
supports up to five bridged single-line voice terminals; however, only two can be off-hook at
one time.
The ZTN78 does not support bridged terminals.
In addition, the TN742 supports
out-of-building, extended, and off-premises stations, while the ZTN78 does not. The ZTN78
supports only a 1.2 Ringer Equivalency Number (REN).
NPE 0
NPE 1
ON-BOARD
MICRO-
PROCESSOR
POWER
SUPPLY
Figure 3-17.
● Ringing Application Circuit
Tip Ring Line (ZTN78) Unique Circuitry
TO
ANALOG
TIP/RING
TERMINALS
This circuit receives ringing voltage from the power supply. It monitors ringing
voltage and current and generates signals to the on-board microprocessor indicating
zero ringing voltage and current. It also detects when a terminal user has lifted the
receiver during ringing preventing the application of ringing to the terminal’s handset
receiver.
3-30