Description:
In some cases, you would like to create a trunk between a third party product and our system

Resolution:
In this case, you are advised to create a SIP trunk on the third party product and a SIP extension on our system.
You may also edit the 'SIP.conf' file (/home/servers/pbxware/pw/etc/asterisk/sip.conf) and use these details to setup the trunk

The following link may give you more information on the issue as well:
http://www.bicomsystems.com/support/C/P/786/359_3482/