Scope
Steps to restrict users to only see contacts who belong to certain groups.
Instructions
Go to Tools > Users > Manage Users.
Find the user > Actions.
Select Link User to Group.
Select the Group Type that you want the user to have access to.
Select the Group Name > Add.
Repeat the process until all the relevant groups have been added > Close.
The user will now only be able to see contacts who belong to those groups.