How does Huawei set the phone off?

Use the call forwarding function: then "Settings → Call Settings → Call Forwarding → Voice Calling → Always Forwarding → Enter the number" in the mobile phone and confirm. If you want to prompt that it is closed, please enter a number that is currently closed. If you want to prompt that it is empty, please enter a number that does not exist or has been used. After using this function, all your incoming calls will not be answered normally, but you can make calls and send and receive short messages normally.