Graham. wrote:
But it's not a withheld number "The caller withheld their number",
it's an unavailable number "We do not have the number to return the call".
Probably from abroad.

Can't say I'm up enough on the systems to know if that difference is
significant or not.

If I was dishonest enough to do this, I would present a UK geographic number
that has nothing to do with me, It's easy to do with VoIP and would give a
false sense of security to people like yourself who believe that if it's got a
valid number, it's tractable :-)

From my point of view, that's correct. However, I don't think the
police would find it an intractable problem, as anyone would have put
full traceability (which is probably what you meant to type :P ) into
the systems. For bug tracking, if nothing else.

Andy