and to follow up with myself... in case someone else has a similar issue.
mobile calling works fine
Wifi calling does not work at all. 2 different SIMs, tried on different Wiifi networks, same deal, I can't hear anything and they can't hear anything. However, I can now hear the other end ringing, whereas I couldn't before.

I know the 8a is in prerelease... any idea when it might get an update?
And is anybody else on the 8a having a similar issue?

Yes, I'm having the same issue. I have a physical SIM on T-Mobile. WiFi calling worked fine on a Pixel 7 running GrapheneOS. I moved the SIM to a Pixel 8a with GrapheneOS, and WiFi calls go through, but there's no audio on the 8a.

I've deactivated and reactivated WiFi calling multiple times. I've rebooted multiple times. Calls go through with audio just fine, if I disable WiFi calling and always use the mobile network.

Let me know if there's anything I can do to help troubleshoot this.

    alankeny
    Well, it's good news (for me) that it's not just an issue for me.
    But bad news that it is an issue with this build.

      #MeToo

      Any ideas of what might be causing this? I'm on tmobile US, physical SIM.

      I am also having this issue with my Pixel 8a. I have disabled Wi-Fi calling for now to see if the workaround works for me as well.

      Disabling Wi-Fi calling also worked for me so at least there is a work around. I'm on U.S. Mobile (Verizon network) with eSIM.

        razorsedge
        It is a workaround because I can at least still make phone calls with Wi-Fi calling disabled. I am hoping this will be fixed once the GrapheneOS version for the 8a is out of prerelease.

          This is my first time using grapheneos, is there any kind of release cadence?

            We have a prerelease available for the Pixel 8a which is not current GrapheneOS with the latest features and has limitations. It is not up to us to change that but rather AOSP and the stock Pixel OS need to move to current Android first. They're currently on Android 14 QPR1 instead of the current Android 14 QPR2. The last official release of GrapheneOS based on Android 14 QPR1 was before the March release of QPR2, which is what we had to use as the basis for the Pixel 8a prerelease. That means it's missing the improvements made to GrapheneOS in March, April and May other than a couple things we backported. It has the current May 2024 patch level but it's essentially the February monthly release of Android 14 QPR1, not current Android. It's unusual that it was launched with an older Android quarterly release and it's likely because QPR3 is right around the corner about to be released in June in all likelihood. It's premature to expect the full GrapheneOS experience on the Pixel 8a since the stock OS / AOSP is not the latest Android version yet.

            1Dragoon The release notes are available at https://grapheneos.org/releases#changelog where you can see how frequent the releases are. Pixel 8a is not part of the regular releases yet and won't be until the AOSP / stock OS Android version catches up, which will hopefully happen with the June release if it's QPR3 (3rd quarterly release of Android 14) as expected.

              6 days later

              I'm seeing similar issues, although it's not limited to voice calls: all networking functionality is extremely shaky.
              When opening the WiFi network list, one can see that the connection is lost and reestablished every couple of seconds.
              Similarly when disabling WiFi and trying to only use mobile network data transfer: it's all extremely unreliable.

              Already tried factory reset and running without restoring the backup but that didn't change anything.

              running latest release with no problems myself, but like developer said there will be a new release soon that may bring a lot of needed fixes.

              15 days later

              With the latest release, wifi-calling is now working. Phew and many thanks!