Sep 01 2019 11:51 PM - edited Sep 02 2019 12:05 AM
I'm assuming you are using calling plans from Microsoft. So you have a dial plan assigned that includes domestic and international and want to restrict the outbound calling to national?
Grant-CsDialoutPolicy is your friend to restrict outbound calls.
Get-CsOnlineDialOutPolicy shows you the policies available.
And indeed the Global policy is "InternationalAndDomestic"
I would suggest that during your user provisioning process you assign your users with a proper policy.