hermore, you will be able to decide if SIP is the proper tool to use in order to resolve your problem and if so, what other tools you will also need to build the architecture that suits your application better. It is good to always keep in mind that rather than being in an isolated protocol, SIP is part of the Internet multimedia conferencing architectures-a set of protocols that combined can be used to provide multimedia services. FOREWORD Unbeknownst to those outside the field of telecommunications, a quiet revolution is taking place. This revolution is aimed at overthrowing the decades-old technologies, now long past their prime, which are the cor- nerstone of today's wired and wireless telecommunications networks. This revolution will free people from the high cost and low value-add of many telecommunications services, and bring them into the low cost and high value-added services that are the norm on the Internet. The revolution is not being fought with swords or guns, but rather, with technologies- Internet technologies-which are being used to completely redefine the architecture of telecommunications networks. At the lead of this quiet rev- olution is the Session Initiation Protocol (SIP), an Internet standard developed by the Internet Engineering Task Force (IETF). Ever heard of SIP? Probably not-and that's the problem. Up until now, knowledge of SIP and its related technologies has been the domain of the technology elite. However, the changes in the telecommunications indus- try that SIP is causing are important for many people-from technology managers to businessmen to enterprise network administrators. These people don't need to know the details of the technology, but they need to appreciate its importance and understand how it might impact their work. That is where this book fits in. SIP Demystified is not a book for software developers or protocol engineers. It's a book for a much broader audience that helps provide context for SIP and an appreciation for its purpose, basic operation, and relationshi