1. A telephony security system for controlling and logging incoming and outgoing calls between end-user stations within an enterprise at one or more of its locations and their respective circuits into a Public Switched Telephone Network (PSTN), said system comprising: a database controlled by system administrators at one or more enterprise locations containing security rules including the action of permitting or denying an incoming or an outgoing call for each of the end user stations, said security rules specifying actions to be taken based upon at least one designated attribute of the call on the line, wherein said at least one attribute is determined within the enterprise; and a line sensor within the enterprise for periodically determining a call-type of the call, wherein said line sensor includes means for determining at least one attribute of each call and for performing actions on selected calls based upon the determined at least one attribute of the call, in accordance with said security rules and wherein the line sensor senses both incoming and outgoing calls and does not interrupt the calls unless specified in said security rules.