Disable call between some extensions on asterisk

We have a asterisk VOIP Server, we need a application like a control panel, where we could EASY create the contexts for the asterisk server to alow or block a specific extension reach another specific one. Lets say a webpage, where you can "see" all extensions on the server, by selecting one of them, we could select only the extensions he could dial, or which ones they cant... either way its ok. Any questions please ask.