They call regularly and nothing on the other end

Asked for a certain staff member but I could tell from the background noise they were in a call centre. I said they were unavailable and is there something I can help with. They said they would call back later. I said mate if you don't tell me what it is in relation to, you won't get to speak to him. They hung up on me.

I answered after one ring, said hello. Nothing from the other end; they hung up after several seconds. Assume scam, phishing, or maybe wanting me to answer in language other than English?

Scam voodafone