So I have been attempting to troubleshoot the exact bug the OP posted above, which is a failure of Bluetooth calls to connect and sync audio in my Tesla Model 3 across multiple phones, multiple versions of Android and LineageOS, and multiple Tesla firmware versions for quite some time.
I believe the problem is *not* due to phone hardware alone. I believe this bug results from a combination of bad code somewhere in the Tesla Bluetooth firmware that, when combined with the rewritten Bluetooth stack in AOSP, Android Oreo (8) and Android Pie (9), on which LineageOS is based, causes Bluetooth audio to improperly connect resulting in a short series of pops/stutters upon connecting a call, and then silence.
I have completely un-paired / deleted Bluetooth pairing on each of these phones with full resets of the Tesla computer and phones before re-pairing, with no luck. I have also completed a "scrubbing" of special characters from my phone contacts as it was suggested this caused problems in another thread. Neither of these fixes helped.
Here is what I've tested so far:
Tesla Model 3 with Firmware 2019.12.1.2 (and several previous versions post 9.0):
Samsung Galaxy S5 / LineageOS 14.1 (Android 7) - WORKS
Samsung Galaxy S5 / LineageOS 15.1 (Android 8) -
DOES NOT WORK
Samsung Galaxy S5 / LineageOS 16 (Android 9 "Pie") -
DOES NOT WORK
OnePlus OnePlus 3T / LineageOS 14.1 (Android 7) - WORKS
OnePlus OnePlus 3T / LineageOS 15.1 (Android 8) -
DOES NOT WORK
OnePlus OnePlus 3T / LineageOS 16 (Android 9 "Pie") -
DOES NOT WORK
The above testing leads me to believe that the bug is not in fact a hardware bug, but is a code mismatch between the updated Bluetooth stack in "stock Android," AOSP (which is also on Google Pixel phones) and LineageOS, and some code in recent Tesla firmware updates. It may have to do with the introduction of support for new Bluetooth audio codecs by Tesla which do not properly "handshake" with the code in AOSP / LineageOS to identify which protocols / codecs to use to send audio to and from the car. I have not yet tested phone firmware from vendors as I generally do not like outdated, bloated, closed source software on my phones.
There are several active bugs in the
LineageOS Gerrit code review system and
bug tracker system which suggest some developers are aware of Bluetooth audio problems across multiple devices, but I am unsure what code is causing the issues and whether these are related to our Tesla firmware bugs at all. Bluetooth code appears to be a very messy business indeed.
If anyone has suggestions of code that could be the culprit, please let us know and/or submit to LineageOS upstream and/or AOSP upstream, or submit to Tesla.