When a call comes into our group all the agents get an audible ringer even if they are in another call.
This will happen if you are using the attendant setup for Skype for a resource line. You cannot stop the calls from coming through and generating pop ups to all the lines without changing the setup of the resource line. This can be done by your Pinnacle Department Manager.
You can adjust how the sound outputs when you are on a call on the Windows Client in Options>Ringtones and Sounds>Sound Settings>Communications. This should have options to mute or reduce volume levels of other notifications while in a call.