Switching the microphone to mute
When a call is active, the microphone can be muted.
1. "Telephone".
2. "Active calls".
3. 
"Microphone mute"
A microphone that has been switched to mute is automatically reactivated:
▷ When a new connection is established.
▷ When switching between call parties.
See also:
Owner's Manual for Vehicle
Thank you for choosing a BMW.
The more familiar you are with your vehicle, the better control you
will have on the road. We therefore strongly suggest:
Read this Owner's Manual before starting off ...
Contacts
...
Treble, bass, balance, and fader
▷ "Treble": treble adjustment.
▷ "Bass": depth adjustment.
▷ "Balance": left/right volume distribution.
▷ "Fader": front/rear volume ...