I did not return call because they did not leave a message on answering service. My rule for calls from numbers I am unfamiliar with is simple - IF THEY CAN'T LEAVE A MESSAGE, IT COULD BE A SCAM.

No. This Call Centre Is Based In WA With A Sydney Extention.
The Number Is IINET Internet Callback. It's All Good. No Telemarketers!

I don't think it's legitimate if AAPT are making multiple "return" calls to people who aren't with them. To me, that seems to fall under cold-calling telemarketing.

The number AAPT uses to reply to Customer enquiries

Nothing wrong with that.

Your call type question does not cover this type of legitimate call

This is AAPT's offshore call centre (Phillipines) returning a call to you.

to many pranks

This number is AAPT

I am overseas at the moment with my Australian Cell phone and I had 7 missed calls from this number.  Thank god I didnt answer them or it would have cost me a fortune.  Absolute nuisances.

AAPT