Note that the commands used in "exten =>" lines in extensions.conf are called applications. A list of these can be obtained from the Asterisk console with the command

  show applications

To get help on a particular command, try

  show application command

Another good source of information about Asterisk is Voip-Info.Org. For example, detailed documentation on commands can be found here, while information about extensions.conf can be found here.

Troubleshooting Asterisk PABX Software:

Loop and Ground and Kewl, Oh my!
In New Zealand, Telecom uses Loop-Start on all PSTN lines except on business lines where you've explicitly requested Ground-Start (or Earth-Start as Telecom call it). So if you're using Zaptel with Asterisk set your signalling to fxsls or fxols.
Command 'showparkedcalls' already registered (or something close enough)
Remove '' from /usr/libs/asterisk/modules - do NOT simply rename it - Asterisk seems to try to load ALL modules!
I get an error message "Ouch ... error while writing audio data Broken pipe" from Asterisk
This error is from mpg123, not asterisk. When asterisk dies, mpg123 complains. The error that killed * is either above that message or available using GDB if it is a segfault etc. You probably have a configuration error.


SIP callgroup feature similar to ZAP groups : Could not find information whether this is possible. See also:


Be VERY carefull with your settings and setup when using any form of DNS (try to avoid using DNS if you can). The SIP stack is written in such a manner as to cause it to lock solid and hang if it is unable to resolve a DNS entry for any reason whatsoever. This includes using multiple entries for hints on extension definitions. such as:

exten => 600,hint,SIP/600&IAX2/600