No, Wi-Fi calling does not automatically switch to cellular. To ensure that you are using the most reliable connection available, it is important to make sure that your device has a strong and stable Wi-Fi signal before enabling Wi-Fi Calling in your settings. If you experience a weak or unstable signal while attempting to use Wi-Fi Calling, it may be best to manually switch back over to Cellular Network for voice calls in order to maintain the highest quality of service.