If you have more than one audio output device, for example a headset and speakers, you can set one of the audio output devices as an Additional ringer which helps prevent unintended missed calls when the meeting is only ringing on one device.
To configure an additional audio device, select the Settings icon (Figure 1):
Figure 1 Settings
Select the Meetings tab and select the relevant device in the Additional ringer drop down list (Figure 2):
Figure 2 Additional ringer
A secondary audio device will now be allocated and incoming meetings will initiate ringing in both audio devices.