So I use a VPN for everything on my graphene is pix 6. I have WiFi calling enabled.
What are the privacy concerns with WiFi calling?
What can my phone network see if WiFi calling is enabled?
Can they see the WiFi networks I connect to?

WiFi Calling basically works like a VOIP service. Your phone connects to a website owned by the cellular provider and streams your audio to them, then they route it to the other caller like normal.

WiFi calling is good for privacy because it allows you to make calls without connecting to the cell network. When you are on the cell network, your location can be tracked using triangulation and thus you will want to keep it off (Airplane Mode) when you can.

When you use WiFi calling, your cell provider will see the IP you are connecting from. If you're using a VPN then they will only see the VPN IP address. Also, their web server likely uses encryption. If it does, then only the phone company can hear your calls. If there's no encryption, then the VPN or ISP will also be able to listen in. You could probably test whether WiFi calling is encrypted using a tool like Wireshark or you could maybe just ask the company.

All of this should also apply to SMS texts sent over WiFi as well.

    roddyd hi thank you for this helpful reply.
    So ive testee what you said regarding the airplane mode and WiFi calling still works.
    The only thing I'm confused about is if I disconnect my VPN, it blocks the internet for everything, except WiFi calling. I'm still able to make phone calls.
    Does that mean that WiFi calling uses a different path to the internet vs everything else ?

      L8437 Hm, I don't know about that. It's worth investigating. I am going to try to replicate it using Wireshark and get back to you. It could be some feature I don't know about, but this could also be a bug.

      I just tried it on my phone and you're right, WiFi Calling bypasses the VPN. This is honestly a huge letdown since it means your IP is tracked by the carrier. I wonder if this is something GrapheneOS can fix.

        roddyd

        The on phone VPN isn't truly robust. Tethered devices and apparently Wifi calling, bypass it.