The "Call availability" option allows all Pro users (Basic, Moderator or Administrator) to turn "on" or "off' the permission to receive IVR calls. If a Pro user is available to receive IVR calls, then he/she can turn “On” the call availability option. Conversely, if a Pro user is temporarily busy or unavailable to receive IVR calls then, he/she can turn “Off” the call availability option.