Using MDA200 and D100 together with Spokes API

I have a solution that uses the MDA200 to allow a D100 headset to be shared between a Soft Phone call and a standard Desk Telephone.

I would like to detect when the MDA200 is switched between the computer interface and the PSTN interface.  Our Soft Phone can do this with the Savi W740.

I get a Talk Button Pressed and HeadsetStateChange (MonoOn) & AudioEnabledChanged(MonoOn) events when the Computer button is pressed, but I don't get any events when the PSTN button is pressed.

Are there events that I should receive from the MDA200?

The SDK COM sample shows the same set of events - nothing when the PSTN button is pressed.

Thanks in advance.

-Paul Wysocki