Caller: Claimed to be from Telstra

Received an unsolicited call on my mobile from a person calling himself "Daniel", with a very sub-continental accent, claiming to be from Telstra ... lot of noise in the background so seemed like a call centre so I held on and all he kept saying was "Are you there ... are you there?", then hung up. I checked the number on=line and it's not listed so immediately blocked it as firstly, I'm with another provider and secondly if it was Telstra (extremely unlikely anyway), they'd never get my business with such a poor CCC approach anyway!