System ISDN settings
The system can be configured with 8 Basic Rate ISDN interfaces. Half of these can be
configured for internal S-bus operation.
The second interface on the CCU and each of the Ports Modules can be programmed as
S-bus interfaces for ISDN to-the-desk.
T
0
interface termination
An ISDN bus must be terminated twice, once at the start and once at the end of the bus.
The Network Terminating Equipment (NTE) will provide the termination at the start of
the bus. The end termination is also provided by the NTE if the BT Versatility is directly
connected to one of the NTE RJ45 sockets.
If ISDN 2 extension cabling and sockets are provided between the NTE and the switch
the end terminating resistor will normally be provided by an ISDN type 2 RJ45 line jack.
In both of these cases BT Versatility T
0
interface does not require the terminating
resistor to be connected and the associated switches in the MDF associated with the T
0
interface must be set to OFF (Default).
Note: In the case of structured cabling if no end termination is provided, the switches in
the MDF associated with the T
0
interface must be set to ON.
S
0
interface termination
An ISDN S-bus must be terminated twice, once at the start and once at the end of the
bus. The BT Versatility S
0
interface emulates the Network Terminating Equipment
(NTE) and consequently is always terminated with 100 ohm resistance. In this case the
switches associated with the interface in the MDF must be set ON.
BT Versatility
Installation and Maintenance Manual
Analogue line module
19
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