Nokia should implement the individual choice of sending the phone# along when calling.
I know that one may be able to reject or allow it within the contract with your operator and that can be overridden by the settings in the phone; in general.
What I mean is that one can set this choice for individuals in the phonebook because in our days there are a lots of people who deny to answer if the phone# is not shown. The other way there are sometimes persons when you call them one is in no need to show the number in this very situation.
Contacts on OVI should be most suitable place where you could edit these needs; and update accordingly.