I'm new to SatNavs, headsets and Bluetooth so maybe I'm making an elementary mistake...  The Sena 20S is Firmware 1.4.

I have a Zumo 390 which supports hand-free phone control but not music/MP3s. Following Zumo manual Step One I paired my Nokia 625 (wp8.1) to the 390. That worked and the Zumo copied over the PhoneBook.  Step Two I connected the Zumo to the Sena 20S as "Second Mobile phone  Pairing" (because I will want to use the Sena 20S "General Mobile Phone One" for A2DP music connection with the phone)

The connection works in that I can dial out from the Zumo and receive incoming calls ringing audibly through the Sena headset, but there is no voice either sent or received.  If I toggle the Zumo from Hands-Free to Handset I can communicate through the cell phone, but toggle back to Hands-Free and nothing from the Sena mic or speakers.

The devices have the following status:-

o  Nokia - Zumo Connected Phone

o  Zumo 390 - Sena 20S1.4 / Enabled / Phone, Navigation

                        - Phone / Enabled / Calls

To add the flakeyness, when trying incoming calls, first attempt after a while the Sena Beeped and announced "Intercom Failure", the second attempt the Nokia BT went down and Zumo pop-up window said "BlueTooth device is disconnected", the third attempt was stable but still no voice.

I don't know what to do next. I looked at the Sena video 1 thru 6 and none seems to cover running a mobile phone off the GPS and music direct from the phone.

Tony