What is a Trunk?
A Trunk is a SIP connection between your phone system and a VOIP provider for inbound and outbound calls. This section covers topics related to managing trunks.
The SIP trunk configuration will depend on your VoIP provider. There are registration based SIP Trunk i.e. via username and password, and IP-based trunks, i.e. PBX public IP is linked to the provider.
Please check with your provider the necessary configuration parameters.
For Sample trunk configurations go to: V3 Examples - Trunks
Don't forget to configure the Inbound and Outbound routes to properly route the incoming and outgoing calls
The Trunks section
You can find the Trunks section under the Tools menu:
When you click on it, you can see all the already existing Trunks or configure new ones:
Create a Trunk
If you want to create a new trunk click on the 
button and enter:
the Trunk Name
the Domain/Host name (ask the Provider)
Authentication Password
Default User Name
Trunk Registry string (which is usually defaultuser:password@host)
Before adding the new trunk, remember to activate it by clicking the Active flag
Edit/Modify a Trunk
Once a trunk has been created, you can edit it to change default values:
You can also duplicate a trunk (Clone Trunk) and modify the copy.
Settings
In the Settings Section you can change general settings inserted at trunk generation (like name, default user, password, context and so on) plus a set of other parameters (in this section and in the Advanced and Other Fields).
In the following example you have all the default parameters for the demo trunk (configured during installation):
Advanced
Other Fields
Refer to the official Asterisk documentation for further information about the Voice service configuration
Monitor Trunk Status
To monitor the trunk registration status go to Realtime in the Voice Section:
and then click on the tab Trunks:
In the trunk realtime environment you see:
Trunk Status, which shows status of a SIP trunk registration to motion server
Registry, which shows SIP registration status when Motion registers as a client to the provider.
You can also obtains the same result by clicking on Go to Realtime Trunk on the trunks list command menu:
