دانلود کتاب IP Telephony Unveiled

The phone service in the United States is one of the most useful and reliable services ever invented. So reliable that we are astounded when we pick up a phone and there is no dial tone. Through all kinds of weather and heavy usage, we rely on the phone system to transmit our voices, fax our documents and be available for Internet connections. Therefore, when managers are told that there is a more efficient replacement, their "Why switch?" response is one that must be answered. The response must also be persuasive, demonstrating that the new way to do things is better than the old.
The new wave in this case is IP telephony (IPT), or the placing of voice clients and voice applications on an IP network. Approximately ten years ago, I worked for a company with a programmed phone system and at the beginning it did not work well. Furthermore, moving to another cubical generally required changes in the phone system that didn't always work as expected. Therefore, the idea that you just plug phone devices into the network is a strong argument in favor of adopting IPT.
IPT technology is here and is reliable, a point stated and restated in this book. It is written at the level of the manager considering the adoption of IPT, there is very little in the way of technical arguments. Most of the points in favor are made using examples, such as in K-12 education. One of the strongest points made in that area was the possibility of a bomb or other threat being phoned in to a school. With IPT, the conversation can be automatically saved as a WAV file and the recipient can dynamically dial up the police and have them be privy to the conversation as it is happening. It is a sad commentary that such an example can no longer be considered an extreme one.
Even though I believe that the author does a bit of overselling of IPT technology, Cisco Systems provides IPT services, the book sold me on the value of IPT. If you are considering the adoption of IPT or are just interested in what it can do for you, then this book is a primer that will answer most of your basic questions.