Former Australian dialling codes
The format of telephone numbers in Australia has changed over time to allow for the expansion of the subscriber base as technology has improved. == Introduction of area codes (pre-1990s) == The introduction of subscriber trunk dialling was slow, partly because of the distances of exchanges in some areas and partly due to the use of manual exchanges well into the 1980s.
Source: Wikipedia — Former Australian dialling codes (CC BY-SA 4.0)