Sena announced a new feature on December 29, 2015, 2:36 PM:
We were able to add a second A2DP profile to the 20S through the v1.6 firmware update. If you pair a device using Mobile Phone pairing then it will use HFP and A2DP and if you pair a second device using Second Mobile Phone Pairing then it will also use HFP and A2DP.
This is great news. The new manual states that the audio will overlay with Intercom (not blank it out because of a higher-priority). This has been what we wanted since the first 20S units were shipped. Last night, my friend and I sat for almost 2 hours in the living room with helmets ON, iPhones and Zumos in our laps. Here are our experiences:
1. When the Zumo pairing to the Sena 2nd phone port is attempted "as a phone" (in the Zumo pairing option screen), it tries to use pass key 1,2,3,4. The manual states that it's looking for pass ken 0,0,0,0. I cannot find any place to change the pass code to be accepted, either on the Zumo device or the Sena device. So pairing as a phone from the Zumo was impossible. Still searching on the Zumo forums to see if the pass key can be changed to 0,0,0,0 to be compatible with the Zumo. This was never a problem when pairing the Zumo as a phone to the Sena first phone port.
2. When the Zumo is paired to the Sena 2nd phone port as an "Audio Device" (the other option in the Zumo pairing screen), it works. No pass key needed. HOWEVER, the audio is not in stereo. It's raspy, loud mono. Sounds bad.
3. When the Zumo is paired to the Sena as a GPS device using the "Audio Device" option in the Zumo pairing screeb, the audio is indeed in glorious stereo. HUH?
4. When the Zumo Lady speaks while the connected to the Sena as a GPS device as in #3 above, the Zumo routing and beeps/alerts take priority over intercom. Intercom gets totally blanked out for 5 to 8 seconds each time.
And while we were at it, we tested other functions that's we'll be using continuously while riding in a group:
1. When in group intercom, user cannot initiate a phone call by pushing the phone button. The phone button seems to do nothing at all. In fact, no one in the group can initiate a phone call while the group intercom is active. The group intercom must be terminated before anyone can make a call.
2. When in group intercom, no one could leave the group by using the double-tap and saying "group intercom". I don't know of any other way for a person to leave the group. Is there one? Since initiating a phone call doesn't work when in group intercom, how does one leave the group to initiate a call? The only way we could do it last night was for the group originator to terminate the entire group. Only then could someone initiate a phone call from the Sena.
3. When in group intercom, it was possible to answer a phone call from an external person. The phone button did indeed cause the Sena to answer a phone call. The phone button does NOTHING except when used to answer an incoming phone call while in group intercom.
This are our observations. I hope other Sena power users can test these conditions and either prove or disprove our findings.