When Jitsi receives a call it should first check to see if the caller's number or URI is already within the user's "buddy contact list". If it is, it should display the name/description of the contact information. If it isn't it should try to display the caller ID as it already does now (caller name sent by remote peer).
So whenever there's an incoming call Jitsi should search through the user's contact list (external contact sources like LDAP can be ignored because it might introduce delays in call reception/display).
If there's a match then
display contact name
display peer caller name/description, if available.
Unless I missed something, Jitsi currently can't do this.
Should I post a feature request?