In order to capture debug and syslog messages from your SPA3xx, SPA5xxG, SPA9xx, and WIP310 IP phones you need to enable debug and or syslog and either have a syslog server on your network or Wireshark running. [Wireshark will display debug/syslog messages with the "syslog" output filter].
Here is a link to a document describing using syslog.
Turn on debugging and or syslog messaging on your phone as follows
[You don't need both debug and syslog, debug is sufficient if you are capturing data for support]:
1. Determine the IP address of your syslog server
c:\ ipconfig /all [Windows]
$ ifconfig -a [UNIX]
For this example, assume a syslog server IP address of 192.168.0.200
2. Configure your phone by directing your browser to:
3a.Enable Debug Messages by editing the following fields:
i. Phone's web-ui > System tab > Optional Network Configuration > Debug Server: <IP address of syslog server> Example: 192.168.0.200 [if you are capturing with Wireshark, you do not need to use a valid syslog server's IP address, any "fake" address can be used, example 10.0.0.1]
ii. Phone's web-ui > System tab > Optional Network Configuration > Debug Level: 3
iii. Phone's web-ui > Ext N > SIP Settings > SIP Debug Option: full
3b. Enable Syslog Messages by editing the following: [step 3b is not needed if you have enabled Debug]
Phone's web-ui > System tab > Optional Network Configuration > Syslog Server: <IP address of syslog server> Example: 192.168.0.200
4. Scroll down and click Submit All Changes
The Phone will reboot and send all debug / syslog messages to the specified IP address of the syslog server.
[Don't forget to make sure that your syslog server is running and that its IP address is what you configured on the phone.]