As I am expecting a call from someone whose number I don't know, I answered this call. As soon as I answered, the call disconnected. I tried calling this number from an unlisted landline (which means the number shows as "private"), and got a voice mail saying that the "mobile number I have called is currently not accepting incoming calls". To me, when a legitimate caller dials a number, they don't hang up when you answer. It sounds at least like call-centre spam to me.