Why Know These Variables? 

The variables shown in this article will determine what is shown for caller IDs and helps dictate where that data is pulled from to help aid in understanding what these options are and how they function. Additionally, why some caller IDs do not reflecting as expected.

CalledNum

The CalledNum variable holds the dialed/destination number, which determines the routing for the incoming. It is common for incoming INVITE messages to have the dialed/destination number in multiple SIP fields in possibly different formats. Typically the dialed number is found in the RURI : User Part or To : User Part, but this may vary. 

To route an incoming call, the system first checks if the CalledNum variable matches one of the DIDs listed in the SIP Trunk settings. It requires an exact match, so the format of numbers entered in the list, must match that of the SIP field set as the CalledNum variable. If the CalledNum variable does not have a match in the list of DIDs in SIP Trunk settings, the system routes the call to the general routing option that is configured for the SIP Trunk. The general routing option of a SIP Trunk (the Catch All rule), can be configured in the SIP Trunk settings under the Route calls to section of the General Tab.

CallerName

The CallerName variable holds the Name of the Caller (CNAM), used to present the Caller’s identity provided by the SIP Trunk Provider to 3CX extensions. Typically this variable is read from the From : Display Name but this may vary.

In cases where SIP Trunk Providers don’t send the CNAM,  even though acceptable, the CallerName variable should be set to a SIP field with a non-empty value, even if the field contains the Caller’s Number .

CallerNum

The CallerNum variable holds the Caller ID of the calling party, used as the incoming call Caller ID presented to extensions, used in reports and in Number Blacklist to reject calls, and more. Typically this variable is read from the “From : User Part” but this may vary.