A type of internal telephone switchboard—typically circuit-switched networks—found in corporations. As telephony continues to evolve to Voice Over IP (or VoIP), companies will use a so-called “hybrid” networks made up of both circuit-switched and VoIP equipment. According to security experts, during this transitional period, present-day security vulnerabilities of circuit-switched networks will continue—­including toll fraud, service theft, the use of unauthorized modems, and eavesdropping on the Public Switched Telephone Network—and new vulnerability issues will emerge. How security professionals deal with these vulnerabilities will depend on the selected vendor, the configuration used, and the particular deployment scenario under investigation.

See Also: Fraud; Modem; Network; Theft; Voice Over Internet Protocol (VoIP).