It would be nice also if you add functionality of contact view on the user account , to enable sellers see how many people viewed there item contact, this is usually in the user profile.

If there is a simple code you can help me with I can add it on item.php

@Dan
If item contact is on item page, then it is equal to item page view, no?

I think it counts the number of time a person clicks on the phone number to view the hidden phone number or maybe it counts the number of time someone uses contact form to message seller for the first time.

Some themes has this feature (ie veronika) but it was never widely wanted.
Integration must come from theme as osclass does not know in what way phone number is shown