The probable causes and handling methods are as follows:
1. If you cannot find another mobile phone, verify that the Bluetooth function of this mobile phone is enabled and the mobile phone can be searched.
2. If the Bluetooth earphone cannot be found, verify that the earphone can be found (entering matching mode). Different Bluetooth earphones can enter matching mode in different ways. For related settings, refer to the headset user manual or find a solution on the Internet. In general, the matching mode is selected when the red and blue indicators flash alternatively.
3. When a message is displayed indicating that the mobile phone cannot be connected to another mobile phone, verify that the mobile phone supports receiving files of this type.
4. In some cases, a mobile phone cannot be connected to other devices because the protocol does not support the connection. In this case, you need to check the Bluetooth protocol support capability between the mobile phone and other devices.