"callable" users

I’‘m working on a Cisco version of this and I’‘ve gotten incredibly far. One of the features I’‘m trying to implement is to rid the necessity of the “phone mappings”. My logic will be if the user’‘s vcard has an extension, I’'ll try to register a JTAPI listener for that extension. The problem is it seems if a user is not in the phone mappings list, any chat window I open up for that user does not have the phone icon, nor can I right-click on them in my roster to call them. Where is this dictated? Thanks.

-Greg