How to turn off the automatic playing of music when I press the answer button on my bluetooth headset whilst idle?

I have an iPhone 4S and a Plantronics Voyager PRO UC v2 Bluetooth Headset. All works well but as I also have it paired with a secondary device when I press the answer button on the Headset to answer a call on that secondary device it turns the "Music" app on and starts playing music when I finish the call on the secondary device and the Headset recognises audio feed from iPhone and thus I hear it in my ear.

Look forward to any help on how to deactive the push button music turn on feature?

Cheers.