E-Book Overview
State-of-the-art SIP primerSIP (Session Initiation Protocol) is the open standard that will make IP telephony an irresistible force in communications, doing for converged services what http does for the Web. SIP Demystified - authored by Gonzalo Camarillo, one of the contributors to SIP development in the IETF-gives you the tools to keep your company and career competitive. This guide tells you why the standard is needed, what architectures it supports, and how it interacts with other protocols. As a bonus, you even get a context-setting background in data networking. Perfect if you're moving from switched voice into a data networking environment, here's everything you need to understand:* Where, why, and how SIP is used* What SIP can do and deliver* SIP's fit with other standards and systems* How to plan implementations of SIP-enabled services* How to size up and choose from available SIP products
E-Book Content
Source: SIP Demystified
CHAPTER
1
Signalling in the CircuitSwitched Network
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Signalling in the Circuit- Switched Network
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Chapter 1 The telephone network, also known as the Public Switched Telephone Network (PSTN), reaches almost every country in the world. We can find telephone sets almost in every house, including simple analog phones, more advanced Integrated Services Digital Network (ISDN) phones, cordless phones, cellular phones, and even satellite phones. Among technologies, telephone systems are astonishingly widespread. All these phones have something in common. They use a circuit-switched network to communicate between them. The PSTN has been around for a long time, and its u