Switching to VoIP

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Chapter 11: Troubleshooting Tools

Looking at captured packets will often tell you what signals a device is sending, but

not why it’s sending them. For that, you’ll need to go to the device’s logfiles and

diagnostic data. Comparing the caller’s account of the interop event with the

receiver’s account will help you reveal the root causes of interop problems.

Project 11.3. Trace Both Ends of a Call Setup

with Log Comparison

What you need for this project:

• Asterisk

• Xten Network’s X-Lite SIP softphone

• LAN

To set up an interop problem in the test lab, we’ll configure Asterisk to require an

MD5 secret for a SIP peer, without informing the SIP client, X-Lite, what the MD5

secret is. This will simulate lack of support for MD5 SIP authentication by the call-

ing endpoint, a common incompatibility. You can require an MD5 secret for any SIP

peer by finding the section for the peer in /etc/asterisk/sip.conf and adding:

md5secret=whatever

whatever signifies any string you want, since our purpose is merely to require MD5

support from the X-Lite SIP client. Once you’ve added this token to the sip.conf file,

issue a

reload at the Asterisk CLI and then launch X-Lite on a nearby PC. Attempt to

place a call using X-Lite configured for the extension number whose SIP peer you

just gave the

md5secret token. ...