Why do some of telephone number start with 1800 and 1300 in Australia?

Question

Why do some of telephone number start with 1800 and 1300 in Australia?

Answer 1

1800 numbers are free when made from a landline phone (other then a payphone) and 1300 numbers are the cost of a local call (on a landline phone other then a pay phone)  no matter how away you are calling from, for example u could be in brisbane and call somewhere in perth and it would only cost a local call provided its a 1300 number