What This Book Covers

Chapter 1 provides an overview of the SIP protocol, its architecture, and its main components. SIP flows are explained and will be essential for the future comprehension on this book. Some important concepts such as codecs, session description protocol, and real-time protocol are presented at the end of the chapter.

Chapter 2 will give you an overview of the OpenSER software. We also cover how SIP requests are processed and the basic concepts of transactions and dialogs after explaining what SIP is.

Chapter 3 is where you will learn how to install Linux prepared for OpenSER and OpenSER itself. After the installation, you will learn how to start and stop the daemon and how to initialize OpenSER at boot time.

Chapter 4 introduces you to the basic scripts and analyzes the default configuration. At the end it shows you some important concepts about routing transactions and dialogs. Be sure to understand the routing basics before going ahead.

Chapter 5 shows how to connect OpenSER to a MySQL database to authenticate all the initial requests. Later in this chapter you will see how to add some security mechanisms to improve your system.

Chapter 6 introduces some important concepts about the user portal. You will learn how to install and do the basic operations with SerMyAdmin. SerMyAdmin is a graphical user interface for OpenSER that aims to make your life easier in the administration of the server.

Chapter 7 teaches you how to connect to the PSTN (Public Switched Telephone Network) using a gateway. Details on how to connect to an Asterisk Server or a Cisco gateway are provided.

Chapter 8 introduces you to the concepts of call forwarding to a voicemail server. You can use Asterisk as a voicemail server connected to OpenSER. Concepts such as failure_route and AVPs are presented in this chapter.

Chapter 9 covers SIP NAT traversal. It introduces the problems and techniques to traverse NAT devices for SIP communications.

Chapter 10 is about billing. It teaches you how to send call detail records to a RADIUS Server and how to rate the calls using a GPL tool known as CDRTool.

Chapter 11 introduces some tools to help you in stress test your platform, detect voice quality problems, and trace SIP calls.

In After Words you can see last minute information covering newer versions of OpenSER, not available when the book was written.