Phone sound is from speaker instead of Bluetooth earphones during call

Problem phenomenon:

After connecting the Bluetooth earphones, music/video sound comes from the earphones but when answering a call, the call sound comes through the mobile speaker.

Solutions:

After connecting the Bluetooth earphones, music/video sound comes from the earphones. That proves the earphones are normal. 

Please follow the path to change the sound channel of phone calls:

During calls > Select the speaker icon > It will show Bluetooth device name/Phone/Speaker > Choose the one you like. 

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