Book Image

Building Telephony Systems with OpenSIPS Second Edition - Second Edition

By : Flavio E. Goncalves, Bogdan-Andrei Iancu
Book Image

Building Telephony Systems with OpenSIPS Second Edition - Second Edition

By: Flavio E. Goncalves, Bogdan-Andrei Iancu

Overview of this book

OpenSIPS is a multifunctional, multipurpose signalling SIP server. SIP (Session Initiation Protocol) is nowadays the most important VoIP protocol and OpenSIPS is the open source leader in VoIP platforms based on SIP. OpenSIPS is used to set up SIP Proxy servers. The purpose of these servers is to receive, examine, and classify SIP requests. The whole telecommunication industry is changing to an IP environment, and telephony as we know it today will completely change in less than ten years. SIP is the protocol leading this disruptive revolution and it is one of the main protocols on next generation networks. While a VoIP provider is not the only kind of SIP infrastructure created using OpenSIPS, it is certainly one of the most difficult to implement. This book will give you a competitive edge by helping you to create a SIP infrastructure capable of handling tens of thousands of subscribers. Starting with an introduction to SIP and OpenSIPS, you will begin by installing and configuring OpenSIPS. You will be introduced to OpenSIPS Scripting language and OpenSIPS Routing concepts, followed by comprehensive coverage of Subscriber Management. Next, you will learn to install, configure, and customize the OpenSIPS control panel and explore dialplans and routing. You will discover how to manage the dialog module, accounting, NATTraversal, and other new SIP services. The final chapters of the book are dedicated to troubleshooting tools, SIP security, and advanced scenarios including TCP/TLS support, load balancing, asynchronous processing, and more. A fictional VoIP provider is used to explain OpenSIPS and by the end of the book, you will have a simple but complete system to run a VoIP provider.
Table of Contents (21 chapters)
Building Telephony Systems with OpenSIPS Second Edition
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Debugging the routing script


To better test and debug the routing script, we will use the xlog() function as a way to insert debugging and informational messages in our script:

loadmodule "xlog.so"
xlog("L_ERR","Marker 480 ruri=<$ru>");

You can check the latest XLOG messages with the following command:

tail /var/log/syslog

The t_on_failure() function tells OpenSIPS to handle the SIP failure (negative/unsuccessful replies) conditions. Failure conditions in this context are error messages of codes, 4XX and 5XX. When you call t_on_failure() just before calling the t_relay() function, you will tell OpenSIPS to transfer the control to failure_route[missed_call] when a failure message is detected:

Note

IMPORTANT: OpenSIPS does not execute the failure route when you perform t_on_failure() but executes it in the future when (if any) a SIP failure is detected:

t_on_failure("missed_call");

The first part of the failure_route section handles cancelled messages (487). The script simply terminates the...