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Signalling from Terminal Exchange (ARB) to Transit
Centre (ARM)
See the signalling diagram in fig. 10 which shows, first, the ordinary Type B
calling, call-confirmation and proceed-to-select signals. In reply to the proceedto-select
signal the tariff zone (T) and class (K) are sent to the transit centre,
and at the same time GA to the subscriber. After the sending of selection
information by the subscriber and after tariff determination in the transit
centre the code receiver in the terminal exchange is called by a pulse of 25 ms
duration. When the code receiver has been connected to the repeater, an
acknowledgement is received also in the form of a 25 ms pulse. The tariff is
then sent in 2-Out-of-5 code (denoted Z in signalling diagrams). The subsequent
signals are Type B as already described.
Signalling From TxA to TxB
The signalling diagram in fig. I 1 shows the signalling on the various circuits
for establishment of a connection TxA-ARB-ARM-ARM-ARB-TxB. The
signalling on the subscriber lines TxA and TxB is shown for single current.
Fig. 10
Signalling on circuit between terminal exchange
ARB and transit centre ARM for call from subscriber
on ARB
Trunk circuit between the exchanges
A-subscriber tariff zone
A-subscriber class
Tariff information Signal
Selection information, i.e. called subscriber's
number
Time signal
B subscriber's answer-back
B subscriber's number
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