Cisco IP Telephony: Planning, Design, Implementation, and Operation of the IP Telephony Network, is a guide for network engineers as they go through the deployment of a Cisco IP telephony (IPT) solution. Although an IPT system brings several benefits to an organization, understanding all the components of that system is necessary for a successful implementation. Engineers tasked with implementation must also keep in mind that the architecture they are installing must be scalable in the future. The authors of this book, Ramesh Kaza and Salman Asadullah, have taken an approach to address the questions that come to these engineers while planning, designing, implementing, and operating the Cisco IPT solutions. The deployment process has been divided into four phases: Planning, Design, Implementation, and Operation (PDIO). Each phase provides specific details about the tasks involved and best practices for successful implementation of the IPT solution.