I picked up the call but there was no answer, just a short electronic sound and nothing further. Probably a telemarketer.

Had trouble hearing them, but got the gist that they wanted me to change power supply companies to whoever they were promoting.
this was the second time today they called, first time they hung up right away when I answered.

Caller: I don't know

Was very noisy like call centre. Hung up as soon as I answered and said where I was from.