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Recall to operator. If an incoming call is not answered by an extension
within about 30 seconds, the operator is recalled automatically. If an incoming
call is placed on an automatic waiting (camp-on) circuit for an
engaged extension and the latter does not become free within about 30
seconds, the operator is also automatically recalled. This ensures good
telephone service.
Busy indication. The individual extension keys on the console are fitted
with busy lamps. This makes for quicker switching and better telephone
service.
Announcement of incoming call. The operator can announce incoming calls
both to free and engaged extensions. When the operator enters an engaged
circuit to announce a call, a special warning tone is issued.
The exchange can be supplied with extra equipment for the following traffic
facilities:
Group calls to a group of extensions dealing with the same kind of
business. Extensions allotted to a group number can also be called on their
individual numbers.
Visual paging both from extensions and from operator.
Automatic tie lines to other private exchanges.
Subscriber meters for metering dialled trunk calls when the public exchange
has facilities for transmission of metering pulses.
Trunk discrimination equipment, which prevents unauthorized extensions
from initiating calls over the trunk network.
Operator's Console
The operators console (fig. 2 and 3) allows efficient telephone service.
On the left-hand side of the console are the exchange line keys. Each
exchange line is represented by a key, a call lamp and a supervisory lamp.
The switching equipment, which is placed on the right, consists of 15 keys
including splitting key and keys for night service, serial calls, paging, cancellation,
bell signal, and transfer to extensions.