Xiaomi 12 secondary card point started without response.

Didn't turn on the VoLTE switch of the mobile phone.

The reason why Xiaomi 12 secondary card point is unresponsive may be that the VoLTE switch of the mobile phone is not turned on. Its Xiaomi 12Pro supports the use of two calling cards at the same time, but the secondary card needs to turn on the VoLTE switch of the mobile phone to use it. To turn on the phone, you need to go to Settings-Dual Card and Mobile Network-Select the correct card number-Click the switch behind volte HD Call, and then start.

Olte HD calling is a technology in the 4G era, which is turned on by default. If the phone turns on volte HD calls, the secondary card can't be used yet. You can manually send a text message to the operator to open it.