ericsson review - History of Ericsson - History of Ericsson

Numbering diagram for the multiple of
the first group selector at Bogota Centro
I six digit numbering
II five digit numbering
76
quench problems. At the same time the high transmission voltage allows the
use of smaller wire gauge, important for an extended local network as that
in Bogota. In non-operated condition the voltage on the subscriber's line is
24 V. Guaranteed operating limits are 22 and 26 V.
Release of a connection takes place from the calling subscriber only (A-subscriber).
Should, however, the called subscriber (B-subscriber) omit to replace
his receiver, the A-subscriber will be released but the connecting circuit remains.
In this way possible malicious calls may be traced. Should the B-subscriber
only replace his receiver both subscribers will remain connected and
an alarm will be issued in the exchange after a certain time.
The trunk final selector tots on a local call in progress and the operator may
break in on this call, disconnect the subscriber not required and establish the
trunk call connection. The operator cannot, however, break in on a trunk call
in progress.
The exchanges are equipped with traffic meters normally operated once for
each completed call. For calls to one or more of the special services the
metering may be suppressed as required by the administration. The system has
provisions for introducing repeated counting during a call.
For cashing charges in coin box instruments the link circuit has been arranged
with current reversal on the calling line, when the called subscriber is
answering. The current reversal is omitted for calls to special services which
are not to be charged.
A number of 500-groups in each exchange has been arranged for PBX-subscribers
i. e. they have been provided with final selectors allowing free hunting
over a number of consecutive lines. These lines may also be called individually
for night service connections to the extensions in the private branch exchanges.