University Peering Program

• Introduction
• Getting Started
• Configuring Asterisk
• Starting Asterisk
• Troubleshooting
• Resources
• Press Release

Troubleshooting

This section briefly describes a number of helpful troubleshooting tools and techniques.

1. Check the Zaptel Configuration. The ztcfg command will indicate (by means of the message "24 channels configured") whether the zaptel.conf file was successfully parsed and loaded.
2. Check the status of the T1 connection. The zttool command displays any detectable alarms, i.e. conditions that will prevent calls from going through the physical connection. You want to see a status of "OK" when you run this command, as opposed to "yellow", "red", etc.
3. Enable PRI debugging. From the CLI, issue this command for the span number defined in zaptel.conf:

   *CLI> pri intense debug span 1

   You want to see a message approximately every 5 seconds indicating that a counter is being reset. It is a bad sign if you see constant messages; read the output to determine the problem.

4. Enable SIP debugging. From the CLI, issue this command:

   *CLI> sip debug

   Place a SIP call to one of the extensions in your extensions.conf file and watch for the SIP session negotiation in the CLI. You will see INVITEs if your configuration is correct and your server is receiving the traffic intended for it.
5. Sniff your network traffic. The following use of the ngrep command will show SIP INVITEsS (as well as other parts of the session negotiation) sent to phone number 18585551212 on device eth0:

   # ngrep 18585551212 port 5060 -d eth0

6. Disable the firewall on the asterisk server. Our standard install of RedHat included a firewall that was blocking our traffic by default. Run the iptables command to see if you have any active firewall rules:

   # iptables --list

7. Open your firewall. Your network firewall must allow UDP traffic on port 5060 from the peer host specified in sip.conf. In addition, UDP traffic from the entire internet must be allowed on the ports specified in your rtp.conf file. You may wish to consider putting the asterisk Asterisk server in your firewall's DMZ.

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