1. A telephony security system for controlling and logging access between an enterprise's end-user stations and their respective circuits into the public switched telephone network (PSTN), comprising: means for defining security rules for each of the extensions, the rules specifying actions to be taken based upon at least one attribute of the call on the extension; means for detecting and sensing calls on the extensions to determine attributes associated with each call; and means for performing actions on selected calls based upon their attributes, in accordance with the security rules defined for those extensions.