Long shot, but maybe someone else will have an idea. I know Fi uses T-Mobile for "compatible" phones, but for some reason, I can't get WiFi Calling to work properly. I have used T-Mobile MVNOs before with WiFi Calling working, but on stock it doesn't even give me the option, and custom ROMs enable but don't dial on WiFi. I tried using the OP dialer menu to force it to enable in OOS, but it is still not working. Anyone have experience with Fi on the OP6? Does WiFi Calling work for you? VoLTE works perfectly fine, but I really was hoping for WiFi Calling. Where I live, ten minutes in any direction is really rural, and LTE signal is nearly impossible to get.