The S-CSCF can
also cancel a session prior to it being established. If a request has been sent but the
ACK has not yet been received, the S-CSCF can use the CANCEL method to stop the
session from being established. The BYE method cannot be used because the session
has not yet been
Chapter 6
Security Procedures in the IMS
The telecommunications industry has changed from one of trusted entities to open
competition and consequently, a less secure environment. While fraud and security
have always been a concern in this industry, never before has there been more opportunity
for breaching networks than today with the advent of IP networks. Add the open
Internet to the mix, and you have a security officer??™s nightmare.
Prior to the privatization of telecom networks (and the divestiture of the Bell System
in the U.S.), accessing a telephone network was granted only to the very monopolies
that managed those networks. Providing access in any fashion was strictly forbidden,
and access was heavily protected. Learning about the various nuances of these networks
was only possible through specialized training learned on the job working for a
telecommunications provider.
Today, almost every major university has degree programs on telecommunications
management, teaching courses on the technologies that enable today??™s communications
networks to work.
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