Hi again William,
Maybe you can request that they fix the following Wiki FAQ entry too: http://www.3cx.com/support/internal-external-call.html
The text reads:
To check whether the IP is local, 3CX Phone System uses the following process:
It queries all IPs assignedto the PC on which it is installed.
Using the subnet masks assigned, it checks whether the IP is local ACCORDING to windows.
In addition, it also checks a configuration file for a list of local subnets. This configuration file can be found in the <inifilename.ini>. >. Local subnets are listed under the section <sectionname> in the following format <format>.
If the IP is considered local, then the call is internal. If the IP is not local, then the call is external.
I believe <inifilename.ini> should be replaced by 3CXPhoneSystem.ini, <sectionname> should be [Network] and format should be LocalSubnets=netid/mask[,netid/mask[...]]
Cheers,
W.