I see you already had this discussed with my colleagues on the phone, however I will add the information here, so other users can also read it.
Zoiper Classic and Zoiper 3 do support "Restrictions". Restrictions will allow you to disable certain parts of the menus and features.
It can be used alone or with provisioning.
Both Restrictions and Provisioning are BIZ features. Please contact us by email to obtain more information,