I decided to answer, an Indian sounding lady, "good morning, I am from energy bill, how are you?" and I said not interested and hung up. Phone did identify it after if hung up as spam.

Suspected spam call -let it ring out - no message left

Caller: Electricity comparison call centre

Called me at 8pm from a noisy sounding call centre claiming to call regarding my ‘electricity services’.
Hung up and blocked. I get calls from the same type numbers all the time, keep blocking but they switch it up and keep calling.