Book Image

Building Telephony Systems with OpenSER

Book Image

Building Telephony Systems with OpenSER

Overview of this book

Related Content you might be interested in

Current Title:

Small book image
Building Telephony Systems with OpenSER
Apr, 2008 | 324 pages
No titles found
Table of Contents (18 chapters)
Building Telephony Systems with OpenSER
Building Telephony Systems with OpenSER
Credits
Credits
About the Author
About the Author
About the Reviewers
About the Reviewers
Preface
Preface
Free Chapter
1
Introduction to SIP
Introduction to SIP
SIP Basics
Server Operating as a SIP Proxy
Server Operating as a SIP Redirect
Basic Messages
SIP Transactions and Dialogs
The SIP Protocol and the OSI Model
The VoIP Provider "Big Picture"
Where You Can Find More Information
Summary
2
The SIP Express Router
The SIP Express Router
Where Are We?
What is the SIP Express Router?
What Software to Use, SER or OpenSER?
Usage Scenarios
OpenSER Architecture
SIP Proxy—Expected Behavior
Stateful Operation
Differences between Strict Routing and Loose Routing
Understanding SIP and RTP
3
OpenSER Installation
OpenSER Installation
Hardware Requirements
Software Requirements
Lab—Installing Linux for OpenSER
Downloading and Installing OpenSER v1.2
Lab—Running OpenSER at the Linux Boot
OpenSER v1.2 Directory Structure
Log Files
Startup Options
Summary
4
OpenSER Standard Configuration
OpenSER Standard Configuration
Where Are We?
Analyzing the Standard Configuration
Using the Standard Configuration
Routing Basics
Summary
5
Adding Authentication with MySQL
Adding Authentication with MySQL
Where Are We?
The AUTH_DB Module
The REGISTER Authentication Sequence
The Openserctl Shell Script
The Functions check_to() and check_from()
Using Aliases
Handling CANCEL requests and retransmissions
Full Script with All the Resources Above
Lab—Enhancing the Security
Lab—Using Aliases
Summary
6
Building the User Portal with SerMyAdmin
Building the User Portal with SerMyAdmin
SerMyAdmin
Basic Tasks
Summary
7
Connectivity to the PSTN
Connectivity to the PSTN
Where Are We?
Lab—Using Asterisk as a PSTN Gateway
Using LCR (Least Cost Routes)
Securing re-INVITES
Blacklists and "473/Filtered Destination" messages
Summary
8
Call Forward and Voice Mail
Call Forward and Voice Mail
Call Forwarding
Implementing Call Forward on Busy or nanswered
Inspecting the Configuration File
Lab—Testing the Call Forward Feature
9
SIP NAT Traversal
SIP NAT Traversal
NAT Types
Solving the SIP NAT Traversal Challenge
Handling REGISTER Requests behind NAT
Handling INVITE Messages behind NAT
Handling the Responses
MediaProxy Installation and Configuration
openser.cfg Analysis
Invite Diagram
Lab Using MediaProxy for NAT Traversal
10
OpenSER Accounting and Billing
OpenSER Accounting and Billing
Objectives
Where Are We?
Installation of FreeRADIUS and CDRTool
Using CDRTool for Rating
CDRTool Architecture
How CDRTool Rates a Call
Summary
11
Troubleshooting Tools
Troubleshooting Tools
Objectives
Built-in Tools
Packet Capture and Trace Tools
Summary
12
After Words
After Words
What's New in Version 1.2.3
Migration from 1.2.2 to 1.2.3 and 1.3.1
Migrating the Script from Chapter 10 to openser 1.3.1
RTPProxy
Areas for Further Investigation
SIP Peering
TLS Transport Layer Security
Development
Common Mistakes
Forum and Training
Summary
Index
Index

Server Operating as a SIP Proxy

In the SIP proxy mode, the entire SIP signaling goes through the SIP proxy. This behavior will help in processes such as billing and it is, by far, the most common choice. The drawback is the overhead caused by the server in the middle of all SIP communications during the session establishment. Remember, RTP packets will always go directly from one endpoint to another, even if the server is working as a SIP proxy.

Previous Section
End of Section 3
Next Section