Sophos XG v18 - Voice Data Only Question

Hello, I am looking to set up traffic on a voice data only firewall. The phone provider recommends to keep HTTP/HTTPS open in order for the phones to work correctly, but we did not want to have traffic going over the internet. Is it possible to have both of those ports open but not allow traffic over the internet?

Added TAG
[edited by: emmosophos at 11:35 PM (GMT -7) on 20 Apr 2021]