You can set the audio file and audio device to use for incoming calls. This is useful if you want to silence the alert, or play the alert from a different speaker.

There are 3 settings you use. All are per-user settings.

General Settings > Also Alert PC Speaker
General Settings > File Location
General Settings > Inbound Alert Device

You must set ALL 3 settings to use this feature.

Also Alert PC Speaker. This is not a good name. It really means to use PC Speaker INSTEAD of your current audio device for inbound call alerts..

File Location: The audio file should be in .WAV format. Be sure to store it in a folder that the user has permission to access. To silence the alert, make a small .WAV file of silence. Example setting value: C:\DT\my_alert.wav

Inbound Alert Device: The device can be more difficult to set. You need to use the name of the device, or part of the name. The setting is not case sensitive. You can get a list of your devices using these steps:
a) Go to DT Menu > App Folder
b) Quit DT
c) Use Notepad to view file pjsip.log
d) See the list of devices like this:
..WMME found 5 devices:
.. dev_id 0: Wave mapper (in=2, out=2)
.. dev_id 1: Microphone (Plantronics C710) (in=2, out=0)
.. dev_id 2: Microphone (High Definition Aud (in=2, out=0)
.. dev_id 3: Speakers (Plantronics C710) (in=0, out=2)
.. dev_id 4: Speakers (High Definition Audio (in=0, out=2)

So, an example setting value would be: plantronics