I have the 20s and 2 bikes. A Triumph Trophy SE with built in bluetooth and a Goldwing with the J&M bluetooth dongle.
On the Goldwing the volume control on the bike works to adjust volume on the 20s. On the Triumph the bikes volume does not work. The only volume control available is on the 20s itself. 
Since the 20s doesn't do auto speed or background noise volume adjustment I'd like for the volume control from the Triumph to work like it does with the Goldwing because the bike will adjust for speed. 
I had tried Schuberth headset which didn't work well for me but the volume control on the bike worked. I was surprised the 20s didn't work that way. 
I know there's difference in bluetooth protocols but why does it work from the J&M dongle but not the Triumph? Is there something that can be done to make the volume control from the Triumph work with the 20s?

The Triumph radio is made by RadioSound and it's called their NTouch line.  http://www.radiosound.com/products.php