set up : 

connecting as shown in video http://support.sena.com/entries/62724154-Mobile-Phone-and-GPS-Pairing-Configuration-4

cell phone to GPS BMW Nav 4 ( equal Zumo 660)

GPS to 20S as GPS

problem:

if having a call, i can select answer on GPS and hear the other side but they don't hear me.

i can hear myself via the speakers in my helmet.

i've made a request about this problem #87061

some one the same problem and maybe a solution?

in the video they say that this configuration you can make phone calls and if having  a intercom conversation, the GPS instructions don't interrupt the the conversation.

the last part is fine , no interruption of the intercom conversation but making calls , no way.

after reading the manual,  it's possible to connect the GPS as "media device"  but can you then hear the instructions of the GPS and can you make then calls? anyone tested this?