Nortel 1000 Installation And Commissioning Manual page 267

Set the switches on the NTBK50
The NTBK50 incorporates three onboard dip switches. The following tables
provide information on the various settings and related functions of these
switches.
Figure 85
NTBK50 with switch locations
Set the switches on the circuit card according to the requirements of your
installation.
Switch SW1 - DCHI configuration (NTAK93 only)
This switch enables and disables the DCHI and sets the operating mode of
the DCHI. It is only used if an NTAK93 D-channel handler daughterboard is
being used. It has no effect when using the NTBK51 DDCH daughterboard.
Copyright © 2003-2007, Nortel Networks
.
Note: The ON position for all the switches is positioned toward the
bottom of the card. This is indicated by a white dot printed on the board
adjacent to the bottom left corner of each switch.
Nortel Communication Server 1000
ISDN Primary Rate Interface Installation and Commissioning
NN43001-301 02.03 Standard
Release 5.5 7 December 2007
Install the NTBK50 PRI card 267