My engin asterisk trunk keeps showing "Unregistered" but my SIP settings are correct? What do I do?

This issue is caused by DNS. To overcome the problem, just open up your command line within asterisk and type: nano /etc/hosts

Add the following host names to your hosts file.

IPAddress Hostname Alias
127.0.0.1 localhost  
203.161.164.69 byo.engin.com.au  
203.161.160.69 syd.byo.engin.com.au  
203.161.164.69 mel.byo.engin.com.au