Section 4 |
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| Meter Pulsing | ||
| Metering pulses were derived from a Pulse Machine that produced
pulses of 200 - 250 milliseconds at varying time intervals, depending on
the charge rate for that particular call, ie local rate, `a' rate, `b' rate,
international rate etc., and time of day, ie cheap rate, standard rate or
peak rate. The tariff rate was selected by the exchange clock and the distance
rate was set by whether the call destination is on the home or parent/local
exchange as governed by the local dialling code used or by stored information
on the drum translator on the trunk network. These pulses operated subscribers
meters on the metering rack in the exchange. Later the pulses were stored
on magnetic tape making billing much simpler. The pulses were transmitted
on the `Private Wire' that accompanies the `A' and `B' wires around the exchange.
When a call was in progress an earth condition was applied to the `P' wire.
This guarded against the intrusion of other callers to that line, engaged
tone being returned to those other callers. Metering pulses consisted of
a +50 volts signal on the `P' wire, duration 200 milliseconds, derived from
a special `Positive Battery' used only for metering. |
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| Subscribers Private Metering | ||
| As the `P' wire did not extend beyond the exchange, subscribers
could not derive metering pulses in the same way as the exchange meters.
As Meter Pulsing is still used to operate some private payphones and call loggers, this article has been shortened. When the facility is withdrawn then additional details may be given.
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| Private Call Loggers | ||
| Quite sophisticated call logging apparatus became available
that could monitor the telephone line and give a printout of the number of
chargeable units used on a particular call, the call duration, cost, the
number called and the date and time that the call originated. At the end
of the review period it was possible to obtain a total cost of calls for
that period though it was not possible to use the information to dispute
the official telephone bill.
The most sophisticated call loggers were computer based and monitored all the exchange lines of a private exchange system, providing detailed statistical analysis of service. They could be programmed to bill individual departments for calls made during a given period also to expose illicit use of a telephone extension as extension number, number called, time, date, units and charge are logged.
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| References | ||
POEEJ Vol 51, 1958 p324 Pulse-Generation and Traffic-Control Equipment for Periodic Metering (P.S. Russell et al)
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Copyright © 1998-2008 THG and contributors |
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