Routing phone audio during call over A2DP, while getting mic from Android Wear

I was wondering if this scenario is feasible at all.
I know the A2DP is a one-way audio stream, but I only need it for the speaker and have the mic on my watch take care of the other channel.
As I read on the forum, a possible feedback-loop might arise, but I just wonder if this is possible at all.
The Bluetooth-dongle that I have now in my car is connected to an AUX-in. I can imagine that this AUX port is a very old one and does not allow for multiple channels to pass through, so speakers only, not speakers + mic. I am afraid I can't buy another adapter to make it work on a hardware level, that's why I was wondering of it is feasible on a software level.

Many thanks for all the help, I am looking forward to your reply!

Kind regards,

Wouter

If the dongle is using Bluetooth A2DP, it won't work as the Android policy manager will force Bluetooth A2DP to disconnect during a phone call.

Thanks for replying!

This makes a lot of sense now.
I guess it is not possible to change this behaviour, even if one has root access to the phone?

To get back to my set-up, is it still possible to choose which one of the two mics you want to use? So either the mic on the watch or the mic of the phone? Or does it also shut off the connection with the watch with an incoming call?

Kind regards,

Wouter

If there is root access to the phone, a person developing a ROM may be able to change this behavior. In the past few years, I've never run across anyone allowing the usage of Bluetooth A2DP audio during a phone call.

I don't know why as you could potentially use a Bluetooth A2DP speaker for audio and the phone mic or external microphone for input. The only reason that I can come up with would be feedback issues where the phone would just squeal. I have seen this when trying to test the speakerphone having the phone too close to my PC while using the PC to initiate the phone call to my cell phone.

That’s one of the things that crossed my mind as well about the feedback-loop.

Anyways, for now I have come to terms with the limits of my old car radio.
What I currently use is a Tasker-like solution, in which I say, that my phone should use the speakerphone when connected to my Bluetooth dongle. Which I guess is also possible with your app, but I expended a bit on it with the logging of the time in my car and toggling GPS.

Thanks again for answering and giving insight in the wonderful world of Bluetooth.

Best of luck,

Wouter

Yes, you could set the "Phone call audio" setting to speaker and it would automatically turn on the speakerphone when you are in a phone call.