There is another provider but I have to know in advance which tests to do…because there is not written in their webpages…
They answered me as I tought:
" I got informed with my technical department colleagues but we do not have configurations for external switchboards. You can try to hear the assistance of the service provider.
I confirm that now the numbering works correctly both in and out and can be used with a switchboard. " …
What can I do ? I yet changed my VOIP provider for another problem with old one. I await 15 days plus expenses for switching the number (number portability) and now I have to change provider again??
Crazy…!!!