Hi can some post me step by step procedure with illustrations on how to block certain extensions from making external call this is important thank you so much in advance
There are two FreePBX Software add-ons that enable you to easily manage this.
http://wiki.freepbx.org/display/FPG/Extension+Routing-Admin+Guide
http://wiki.freepbx.org/display/FPG/Class+of+Service-Admin+Guide