Using A2DP bluetooth device for call audio?


I have been using /e/OS for a while and I am quite enjoying it. My new phone, the OnePlus 6T (fajita) does not have a headphone jack, so I bought a bluetooth receiver to use it with my wired headphones. This works great for media but does not work at all while on a call.

My research so far indicates that Android disables A2DP devices for call audio, since A2DP is just a one-way audio playback. This might make sense for bluetooth speakers but it completely prevents me from using my headphones for calling, which was my main usecase. Ideally, Android should use the bluetooth receiver + cable headphones for audio playback and the internal microphone of the phone as a microphone.

Apps like “Lesser AudioSwitch” do not allow forcing this either. I have however found a solution elsewhere on XDA for an unrelated phone/ROM:

The author notes though that this only works for GSI ROMs, not AOSP, which I believe LineageOS and therefore also /e/OS is based on.

Can somebody suggest how I would achieve this with /e/OS? I would be happy to give up to 30€ to anyone who helps me figure this out, or the project directly.

Many thanks in advance!