Book Image

Building Telephony Systems with OpenSER

Book Image

Building Telephony Systems with OpenSER

Overview of this book

Table of Contents (18 chapters)
Building Telephony Systems with OpenSER
Credits
About the Author
About the Reviewers
Preface
6
Building the User Portal with SerMyAdmin
Index

Differences between Strict Routing and Loose Routing


Loose and strict are different methods of routing SIP messages. Loose routing is new in SIP version 2. When you use loose routing, the R-URI is never changed and backwards compatibility is maintained with the older method (strict routing RFC2543).

The problem with strict routing is in the process of specifying the entire proxy set in the initial request before starting the SIP dialog. The processing throws away the information contained in the received R-URI. The behavior of UAs with outbound-proxy was problematic. The whole system would fail if there was a failure in one of the elements.

The solution, is that loose routing is the correct method. It keeps the target separated from the route. It allows each destination to route the packet and has a mechanism to keep backward compatibility with strict routing. The support of loose routing is indicated by the parameter ;lr.

When the SIP server receives a message, it can decide if it wants...