Caller: Some old bloke?

Rang my mobile, i didn't know number so didn't answer. Rang back to see if it was a scammer using a disconnected number, it rang so hung up as i thought it was a legit number. 20 minutes later the same number rings, i answer bloke on the other end was asking what i wanted, i said you rang me originally, he was adamant that he or no one else had rang me from his phone. Very weird.