Call from this number, caller had an Indian accent and started with "this is a call about the government solar rebate scheme"

Caller: I don’t know.

Scammers, said hello a few time they started saying FU Mofo etc just hang up

I don't not answer numbers I don't know as 9 times out of 10 its scammers. Called back on private number, user busy. Called with my number on and put the call on mute. Says hello a few times and disconnect. All Indian accents. Continued to do this to irritate them. Got told not to call again (very rich from scammers). Called again and they said let's see how long you can keep up. I would have let my phone die before I disconnect the call. Kept one scammers phone line busy for 3 minutes before they disconnected me. Will continue to do this until they stop calling me.