Teamviewer 12 Creating 'Voice Call' on USB Phone

Since upgrading to the latest release (12.0.78313)  when ever I start a Teamviever connection  whilst on a phone call, it creates a second call on my phone with the description 'computer audio.'

I have tried to amend settings to prevent TV from creatinga new call, but everyting I have done so far has not been sucessful.

The phone is a PolyComm CX600 - connected to Skype.  The Skype client on my PC does not show this 'second call.'

Is anyone able to suggest a solution for this, as although it isn't causing a problem, directly, it is rather annoying and means I need to use the skype client to manage transfers, end calls etc.

Thanks