Post-war and on to 1975 (continued)

With annual growth in international telephone traffic at about 25 per cent in the mid nineteen seventies, the 1300 line electro-mechanical AM20 telephone exchange, which had been installed in 1969, was soon in need of expansion. Technology, however, had now moved to the next generation and an AKE stored programme, computer controlled, telephone exchange was ordered from L. M. Ericsson of Sweden for installation at the new telecommunications terminal at Broadway, Sydney, providing increased capacity and diversity of international facilities. It was fully duplicated, with micro-synchronised central processing units and equipped with 2300 lines for national and international circuits. All call switching was controlled by the central processing units and the speech path was established using code-bar switches, similar to crossbar switches but occupying 25 per cent less space. Furthermore, because power was not required to hold the code-bar switch in the operated position, a power failure would not result in the disconnection of calls in progress. Although the exchange and the basic software was supplied from Sweden, a considerable amount of software to meet Australia's particular requirements was written by OTC and L. M. Ericsson staff in Sydney and as new features were evaluated and incorporated, software development continued.[41]

While rapid progress was being made with other communication services and facilities, the 1959/60 Annual Report of the APO disclosed that, of the 539,718 country telephone services, 63 per cent were still manual, mostly magneto, while the automatic exchanges which accounted for 37 per cent of the services were unevenly spread, tending to be located where either growth had been relatively high, or where costs of conversion had not been adversely affected by the need to invest heavily to upgrade line plant.

From 1963, ARF exchanges, using REG-LM, were installed at minor and secondary centres and initially were designed on the assumption that ARM exchanges would eventually provide higher level switching functions. In order to minimise manual switching, automatic access to exchanges in the minor area was provided on a temporary basis to the maximum extent practicable. Some STD was also provided. In accordance with LME's original proposal for minor centres, two ARM 50 exchanges were installed as minor centres in South Australia but it was apparent that they were too costly and, as detailed elsewhere, studies were begun to develop a two wire minor centre. Meanwhile, as the conversion of manual exchanges to automatic could not be deferred, the use of metropolitan type ARF continued, but since the first-in costs of any kind of minor switching centre were found to be higher than previously expected, many of the smaller minor centres which had been proposed could not be economically justified and the switching plans were therefore progressively revised.

Australian Academy of Technological Sciences and Engineering