This morning I got a call from a man who wanted to speak to my late Father . After telling the man that he wasn't in I looked at the display for the last call and it just had 000 as the number so I dialed 1471 and that also had the numer as o double o

Is this a UK number I've never seen it before if it was international it usualy says out of area or unavailable.

Probably computer generated. Thats what these ad companies do.

I am always getting a call from a number 00000000000 which obviously does not exist so I never answer it.
With todays technology it is possible to spoof CLI with any number.

This is a ploy to get around systems that reject incoming calls if the number is withheld. They get through to badger you - but you still don't get their number!

I used to spoof my number years back, anything from the number I was calling to silly numbers like 0000 or 1111 or even 0151 000 0000 etc.

Now I just display a number that when rang back goes straight to a voicemail service.