Issue 21 - February 2000
The equipment should be used on British Telecom lines requiring loop-disconnect or
DTMF signalling only.
The equipment must be connected to direct extension lines, and should not be
connected as an extension to a payphone.
The Ringer Equivalence Number (R.E-N) is 3
1. The apparatus is connected, for 2-wire connected devices, between terminals A
and B or, -for 3-wire connected devices, between terminals A, B and shunt in the
test circuit shown in figure 17. The BT Bell 59D in figure 17 is one which
generates a sound pressure of not less than 65 dB (A weighted) SPL when
measured as a distance of 1m when connected in the test circuit of figure 17 with
three other 59D bells connected across the shunt and A terminals, and
acoustiCally isolated, and which forms the ring detector of a BT telephone No.
8746. Where either the BT Bell No. 59D or the apparatus ringing detector fails to
function as specified in the relevant product standard, no REN is assigned to the
apparatus. (See note 1 of 4.2)
Where the BT Bell No. 59D and apparatus ringing detector function correctly as
specified in the relevant product standard, the procedure for determination of
REN is continued as described in D. 1.2 or 1.3 as appropriate.
2. For apparatus other than that described in D.1.3, and where in the configuration
described in D.1.1 the BT Bell No. 59D and apparatus ringing detector function
correctly as specified in the relevant product standard, additional complete items
of apparatus similar to the original apparatus are then connected in parallel with
the original apparatus. The number of added items of apparatus is increased
10 items of apparatus are connected:
Whichever is the first to occur.
For further information, Refer to BS6305: 1982
The apparatus will interwork with the PSTN up to an internal resistance between
telephone instrument and Main Exchange unit of 40 ohms maximum, and between
DSS and Main Exchange unit of 20 ohms maximum.
Operation in power failure
Exchange line communication in power failure is available through the primary
telephone sets connected for the usage in power failure- When power failure occurs.
20 % of the connected exchange line are automatically switched over to the
designated primary telephone sets.
© Panasonic UK Ltd.
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