TCL 20 Pro 5G Manual page 34

During a call
To adjust the volume during a call, press the Volume up/down key.
End the current call.
Touch to mute the current call. Touch this icon again to unmute the call.
Display the dial pad.
Touch to activate the speaker during the current call. Touch this icon again
to deactivate the speaker.
Make another call.
Make a video call.
Put a call on hold.
Merge calls to start a conference call.
Manage conference calls.
Swap the calls.
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