A fact - which raises a paradox
Most of us have received unsolicited, unwanted phone calls.
Some of us will have put in place 'Call refused if caller witholds their number'.
Some people / organisations need to withold number for quite valid reasons, such as "I am making this call through a company switchboard with only one number but many extensions: if you try to call me back, the switchboard won't know to whom to connect you".
'Number witheld' status is not signified / bleeped / flashed to someone who picks up a company phone, although it's probably somewhere in company rules.
A KC organisation tried to tell me something was awaiting collection: couldn't, because my phone was in 'Call refused if number witheld'. The caller did not know her phone was 'Number witheld'.
The paradox:
is it morally right to invoke 'Call refuse' ?:
do people have a right to expect to get through ?
Is it right to invoke 'Number witheld' ?
Do people have a right to know who is calling ?
But most of all, be careful about what you WON'T get if settings at the two ends of a call are incompatible.