TNG will not cost a call:
If the line/trunk number is 'INTERNAL' or 'VOIP-INT' or 'VOIP-EXT.
If the call action has the wording INTERNAL.
NOTE: TNG is dependant on the PABX output for this information.
You also have an option to setup internal lines as
NO COST under trunk configuration.
What is an internal call and when is it billable?
If the switchboard makes an outgoing call and then transferres
it to an internal extension, this is a billable call and must
be costed.
If the switchboard calls an internal extension, then it is
internal call and at no cost as far as the service provider
is concerned. TNG however needs the information listed above
to know not to cost it.
If an extension phones an extension it is also internal,
as per above example.
Therefore if an outgoing calls is made and then transferred,
the call has a cost.