3com MSR 20 User Manual

E1/CE1/PRI interface is compatible with both 75-ohm impedance and 120-ohm 
impedance. The interface matches different types of impedance through an 8BIT 
DIP switch. By default, all the 8 positions of the DIP switch are ON, as shown in the 
following figure:

Figure 18   Default setting of the DIP switches

8BIT description and settings of DIP switch are given in the following table:

Operating mode 

E1

CE1, ISDN PRI (supported by SIC-1EPRI 
only)

FE1(supported by SIC-1E1-F only) 

Supported service 

Backup

Terminal access

ISDN (supported by SIC-1EPRI only)

Table 5   Interface attributes of SIC-1EPRI/SIC-1E1-F

Table 6   Description and settings of the internal DIP switch of SIC-ERRI/SIC-1E1-F

1BIT Switch 

for 

75-ohm/120-ohm 
options 

ON OFF 

2BIT

ON OFF 

3BIT

ON OFF 

4BIT

ON OFF 

5BIT

ON OFF 

6BIT Switch 

for 

RxRing 

grounding mode 
options 

OFF: RxRing grounding 
via capacitor

ON: RxRing directly 
grounding 

- 

on

1

2

3

4

5

6

7

8