In article ,
Set Square wrote:

And it will stop *all* calls with number witheld from getting
through - possibly including some from your friends.

Most national and local govt departments, plus we
lost a bed vacancy in our local hospital because
the beds woman dials out with number witheld.

Also it does not stop spam from call centres abroad,
and BT themselves seem to have been the first ones
to notice that workaround.

--
Tony Williams.