Under “Audio" you can set whether you want to use the speakers and microphone of your Mac, a desk phone or a connected headset for making calls.
1 Click on Settings and select the tab Audio.
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Speaker and microphone
Specify which speaker and which microphone you want to use to make phone calls, e.g. on a Mac or a connected headset. Use the slider to adjust the desired volume.
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Ringtone
Select the desired ringtone and set the device for sound output.
2 Use the slider to adjust the desired volume.