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| A panel of stepping switches at a telephone exchange. Public domain image via Wikimedia Commons. |
In
Ireland, unlike the UK, we skipped having transistorised telephone
exchanges and went straight from electromechanical (using relays, coils
and motors) step-by-step or more modern crossbar systems to digital
versions. When I was in the boy scouts in the 70s, I remember the
whirring and clicking coming from the small telephone exchange building
adjacent to our den (located in the tennis club building), as the
exchange switched calls. Electrical pulses from a subscriber's telephone
(known as pulse dialling, now replaced by tone dialling)
caused a shaft on one of the mechanisms in the exchange to turn by a
varying angle, the angle depending on the number of pulses. Each number
from 0 to 9 on the dial of a telephone handset generated a different
number of pulses. The shafts on the mechanisms in the exchange had an
arm or arms attached, with electrical contacts on the end of the arm. As
the arm swept around (usually limited to a half circle), it made
contact with another set of stationary contacts, the process enabling a
call to be connected to another number locally. Trunk calls to another
"area code" would be sent to the exchange in Naas to be distributed to
other local exchanges. From what I recall, in the early 70s, either
Byrne's supermarket in Kilcullen or Athy still had a handset without a
rotary dial, sitting near the meat counter at the back of the shop,
presumably dating back to before the days of the automatic exchange.
This is an RTE report from 1989 about the changeover.