I have an unlisted number so this is obviously somebody I don't know (and don't wish to know) using a random number selector.

Caller: Some insurance company

They called me 3 times today. very annoying. Overseas call centre (I called back then hung up)

Scammer from " utilityoffers.com.au "
trying to change elect-trickery supply companies.

Rang them back on another line - some [ curry-muncher ]
in Mumbai answered

Would not give the address of the office in Melbourne
(so I could look at it on Google street view)

This number has called twice today. When I called back it was a very strange dial tone. It rang for a while and then a recorded message said ‘goodbye’ and call ended