When booting my GOS 4a phone, I see a DNS request for <long domain name...>.3gppnetwork.org and then some isakmp packets to their address.
I do not see any reference to 3gppnetwork.org in https://grapheneos.org/faq#default-connections
What is that 3gppnetwork?

Looks like it has to do with wifi-calling.
If so, I was wondering:
(1) Is there a reason for it not to be mentioned in the doc? Like... Am I a special case?
(2) Is wifi-calling activated by default on GOS? I guess "yes" since there is a connection initiated from my phone but I do not see any menu in the settings, though. So still unclear to me.
(3) How did my phone learn the domain name to make the DNS request for?
Thanks!