Hiding Contacts silliness
 

As silly as you are for wanting / "needing" to do this, you do realize that the phone will dial numbers out of an e-mail message? Put 'em there. Not as obvious.

interesting but thats too much for me to be doing...

I got questions about legitimate situations
 

The first is management services:

This can sometimes have the same trappings as a relationship especially if clients don't like one another. This can become a highly legal matter due to the contracts and business relationships involved.

More seriously legal department personnel:

A certain client privilege is in effect when dealing with people and even having their contact information accessible by someone that might use that phone or failing to execute your due diligence in protecting that information may impinge on the clients rights.