
■
3xx Redirection (302 REDIRECT TO SERVER)
■
4xx Client Error (401 UNAUTHORIZED)
■
5xx Server Error (504 TIMEOUT)
■
6xx Global Failure (this is a new status class)
SIP is truly a simple communication protocol that was designed with effi-
ciency in mind but with little thought as to the effect it would have with POTS
lines or how secure infrastructure should be designed. Although considered an
open technology, SIP’s many variants, and the equally many different infrastruc-
ture implementations, make SIP a trivial protocol to exploit today.
Caller ID Spoofing
Caller ID (CID) was publicly implemented in 1987 and was merely designed to
screen calls and to authenticate ...