Setting a secondary ringer
In addition to selecting the audio device you prefer, with Lync 2013, you can set a secondary ringer, as well. For example, you can choose to have your desktop speakers ring in addition to your primary audio device. This can be quite a useful feature when you are using a headset, because without the secondary ringer, the only way you will be aware of an incoming call is via the Incoming Call pop-up notification.
Set a secondary ringer
In the Lync client window, click the Settings icon (the small gear graphic).
In the Options dialog box, click the Audio Device tab.
In the Secondary Ringer section, select the Also Ring check box.
In the list box, select the device that you want to use as the secondary ringer.