I believe this is a company in Varsity Lakes called Salescorp

Yeah, I get these too, and I'm in New Zealand. They ring twice and then ring off. Also engaged if I try and ring back...

keeps calling here too - when answered no-one speaks back but can hear activity in the background - telstra say they can't check the number but that it may be a telemarketer

called and when answered  no one there. then tried to call back and it was engaged

Called over 10 Times, said nothing.

I have now had 4 calls within the last week an I finally decided to ring it back but it was engaged. Now I have found this website I will be ignoring it from now on.