Why can't the Xiaomi 15T Pro switch from 4G VoLTE to VoWiFi?

Question

Accepted Answer

Thank you for your support of Xiaomi. The Xiaomi 15T Pro may fail to switch from 4G VoLTE to VoWiFi due to compatibility differences between the SA/LTE network and VoWiFi protocols. When the device is not registered on the Standalone (SA) 5G network, enabling N1_MODE for VoWiFi can restrict the transition between cellular and Wi-Fi networks. This may result in VoWiFi registration failure or prevent voice calls from being routed through Wi-Fi.
This situation is caused by network protocol behavior and is not related to hardware performance. To resolve the issue, please update your device to the latest system version, which includes optimized network switching logic and improved VoWiFi compatibility.
After updating, your device will be able to manage VoLTE-to-VoWiFi switching automatically, ensuring stable call connections, smooth transitions between networks, and consistent communication quality.