Power Fail; Analogue; Isdn - BT Versatility Installation And Maintenance Manual

Power fail

When planning the extension wiring for the system, consideration should be given to the
use and location of Featurephones and 2-wire extensions.

Analogue

In the event of a total system power failure, at least 50% of the equipped lines are
switched to extensions. Lines 1 and 2 are power-failed to extensions 26 and 27, the last
two extensions on the basic unit. Line 5 is power-failed to extension 34 and Line 7 to
extension 35, the last extensions on each of the expansion boards. These line positions
are summarised in the table below.
Note: If lines are power-failed to extension positions equipped with Featurephones, the
user must replace the Featurephone with a standard 2-wire phone to answer or make
calls. FEATUREPHONES CANNOT BE USED IN POWER FAIL.
Line position
Line 1
Line 2
Line 5
Line 6
Line 9
Line 10
Line 13
Line 14

ISDN

In the event of a total system failure, the ISDN lines will not operate. ISDN devices can
be connected directly to the ISDN NTE or an external S bus, and work independently of
the system.
Power-fail extension
Extn 26
Extn 27
Extn 34
Extn 35
Extn 42
Extn 43
Extn 50
Extn 51
BT Versatility
Installation and Maintenance Manual
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