The 4G icon is displayed in standby mode but changes to a 2G or 3G icon during calls

Problem:

The 4G icon is displayed on the status bar when the phone is in standby mode but changes to a 2G or 3G icon during calls.

Cause:

The VoLTE function is disabled, resulting in the 4G network not supporting phone calls and the phone automatically switching to the 2G/3G network during calls, and going back to the 4G network after the call is ended.

Solution:

If you want to make phone calls using the 4G network, perform the following to enable VoLTE:

1. Contact your network provider's customer service to check whether the VoLTE network is available and whether VoLTE services have been activated for your SIM card.
2. Swipe down from the top of the screen to show the shortcut menu, touch and hold the Mobile data icon to access the settings screen, then turn on the VoLTE HD calls switch. On some phone models, VoLTE is enabled by default and this switch is unavailable.

   After VoLTE is enabled, the HD icon is displayed next to the signal bars of the SIM card.

   

3. If VoLTE cannot be enabled using the preceding methods, your phone may not support the VoLTE function of the corresponding network provider. In this case, call Huawei customer service hotline for assistance.