ShowingVoice (the robocall) is used when you select ShowingVoice in the Agent Notification Preferences. Calls coming from ShowingVoice for confirmation purposes will come from the following number: (877) 351-7469.  If you call that number back, an automated voice states you are calling ShowingVoice and requests you provide a phone number that was used to register you with the system. 

You can turn off ShowingVoice by deselecting ShowingVoice and Call from your Agent Preferences.