How do they get your phone number?

It's a high complicated algorithm.

1. Find a phone number, remembering in Australia all mobile phones start with 041, then you dial it. For example you may choose to start at 0411 000 001.

2. If you get a response, then whoopee, Spam permission granted! Add 1 to the number and continue.

3. If you don't get a response, then that's too bad. Add 1 to the number and continue.

4. Repeat forever.