Restrict a pin code from making outgoing calls


I am very new to asterisk and I am trying to make a few changes on a system that was not created by me.

At my company we have an asterisk box which works ok, the thing is I want to block a user pin from making outgoing calls, but still able to dial a speed dial which includes, mobile fone numbers and other local land line. however I am not sure where to begin.

Most of this question relates to your specific, existing dialplan. That is either generated by a GUI, in which case you need to identify the GUI, and a forum specific to the GUI may be more appropriate, or it has been custom written, in which case you are going to have to provide the relevant parts of here, before we can really understand what is happening.