When I'm calling me

Just got back from a shopping trip and the light was flashing on my answerphone.  Not unusual, it's usually a cold caller.  But when I looked at the caller-ID display the number looked familiar.  Then I realised it was my number.

Well, when I played back the message, it was blank, so I guess it probably was a cold caller.  I know caller-ID can be spoofed so I wonder if this is a new ploy by cold callers to get round those devices that block specified numbers.  Nobody  would think to block their own number.

Or maybe I was calling from an alternate universe but something prevented me from leaving a message.