A2B: Setting up a trunk in A2Billing - 3.4 out of
USERNAME/PASSWORD BASED AUTHENTICATION
If we are using username/password authentication with our provider then we need to set our trunk up manually in Asterisk. We will give that trunk a name and then use that name, instead of the IP address, in the A2Billing trunk setup screen above.
Here’s an example of setting up a trunk with switch2voip.us. Many providers will be similar and provide the connection details you need to enter. These settings go in the file /etc/asterisk/sip.conf.
If you need to ‘register’ with your termination provider enter the register line under the existing [general] section -