Scenario: you're missing calls on the 3CX phone system
Cause: (potentially) 3CX has chosen to ring a device without an audio output (such as an HDMI monitor without speakers)
Fix: you need to specify the audio device that indicates you've got a call
Fire up the 3CX app on your desktop and click the three dots
on the left-hand menu to access your settings. From the sub-menu, choose Audio/Video.
Click the Ringer drop-down list to see the list of devices that 3CX recognises.
Choose a device that has a sound output. This will typically be your laptop's speakers or it could be your headset if you wear it all of the time.