A system and method of telephony security for controlling and logging access between an enterprise's end-user stations and their respective circuits into the public switched telephone network (PSTN). A security policy, i.e., a set of security rules, are defined for each of the extensions, the rules specifying...http://www.google.de/patents/US6249575?utm_source=gb-gplus-sharePatent US6249575 - Telephony security system
