Nortel Communication Server 1000S Installation And Configuration Manual page 347

For the U.K., use DPNSS1 mode. For all other countries, use Q.931 mode.
Table 98
Switch SW1
Switch
SW 1-1
SW 1-2
Switch SW2 — Carrier impedance configuration
This switch sets the carrier impedance to either 120¾ or 75¾. Twisted pair
cable is usually associated with 120¾. Coaxial cable is usually associated
with the 75¾ setting.
Table 99
Switch SW2
Cable type
75¾
120¾
ISDN Primary Rate Interface
2.0 Mb PRI implementation
Down (On)
—
DPNSS1/DASS2
SW 2-1
Down (On)
Up (Off)
Page 347 of 394
Up (Off)
—
Q.931
Installation and Configuration