1. Open dialer
    2. Enter *#*#4636#*#* (*#*#INFO#*#*)
    3. Select “LTE only”, “NR only” or “NR/LTE” as applicable or preferred.
    4. In settings, navigate to mobile network
    5. Disable VoWiFi, VoLTE and VoNR

    No more phone calls!
    If there is no 2G/3G in your area, you can just skip to step 4.
    Outgoing calls won’t work either.
    USSD/MMI including settings like call barring and forwarding may also not work (set/reset, existing settings should be fine).