Hi, I don't know asl this since an update but I can no longer make and receive calls. When I call my call is terminated immediately. I can use mobile internet and wifi though. My sim card works fine on another one. Everything works fine with the provider. Phone also rebooted several times. I suspect this is due to GrapheneOS. Any tips?

Thanks for the tip. I must have changed a setting. So it is LTE that you have to use and not LTE only. So solved. Thanks

    MorananaroM If changing this setting results in problem going away, your SIM and/or carrier doesn't support VoLTE. If you enable it (by reaching out to your carrier), you'll be able to make/receive calls while having 'LTE only mode' enabled on GrapheneOS.