Nortel Networks Circuit Card User Manual

 NT1R20 Off-Premise Station Analog Line card

The line type, terminating impedance, and balance network configuration for 
each unit on the card is selected by software service change entries at the 
system terminal and by jumper strap settings on the card. 

Each line interface unit on the card is equipped with two jumper blocks that 
are used to select the proper loop current depending upon loop length. See 
Table 71. 

For units connected to loops of 460 to 2300 ohms, both jumper blocks for that 
unit must have jumper blocks installed. For loops that are 460 ohms or less, 
jumper blocks are not installed. Figure 24 on 

 shows the location of 

the jumper blocks on the OPS analog line card.

Class of Service 
(CLS) (Note 1)

ONP

OPX

Loop resistance 
(ohms)

0–460

0–2300 (Note 2)

Jumper strap 
setting (Note 6)

Both JX.0 and JX.1 
off

Both JX.0 and JX.1 
off

Both JX.0 and JX.1 
on

Loop loss (dB) 
(Note 3)

0–1.5 

>0–3.0 

>2.5–3.0 

0–1.5 

>1.5–2.5 

>2.5–4.5 

>4.5–15

TIMP 
(Notes 1, 4)

600 
ohms

600 
ohms

600 
ohms

600 
ohms

600 
ohms

600 
ohms

600 
ohms

BIMP 
(Notes 1, 4)

600 
ohms

3COM

3CM2

600 
ohms

3COM

3CM2

3CM2