Over here, the first two numbers are the state the exchange is in, so some towns along a border might have the other states initial code numbers, the next 2 numbers are the regional area code, the next 2 numbers were the local exchange, and the last 4 numbers actually identified your telephone line .... as an example 02 was NSW, 42 was the Illawarra area, 29 was central Wollongong 3493 was the actual workshop line, 10 numbers to get both correct and in the correct order .... simples
Now I really feel old, that dates back to the mid '80s, but I still remember the phone number of my automotive workshop ....
T1 Terry