[Nexus 6  General] davidnghk:
OK, me again, the "in call speaker" was working fine.

then I broken my screen a month ago, and get it repaired. ( did not try call anyone after repaired )

then I saw the lineage 16 shamu got publish in Mar 01, 2019 https://download.lineageos.org/shamu

I install it, try to call my friend, holy god, NO sound for the "in call speaker", NO sound for the "loud speaker"...

I then remember this post, and get my working "Nitrogen-OS-O-shamu-20180807.zip" but I can't find that gapps, so I use the "open_gapps-arm-8.1-pico-20181216.zip"

after the installation, I make a test call, without any other apps. NO sound for the "in call speaker", NO sound for the "loud speaker"...

I also reflash the radio 7.1.1 v5.5 mention in here https://xdaforums.com/nexus-6/development/fxz-nexus-6-recovery-flashable-fastboot-t3066052 shamu_baseband_D4.01-9625-05.51+FSG-9625-02.118.zip

I also use fastboot to flash the full stock 7.1.1 (N6F27M, Oct 2017) from https://developers.google.com/android/images

nothing works, both speaker no sound.

did the "screen repaired" broke my speaker?

wait a minute, I can play music using the "loud speaker", but during the phone call "loud speaker" does not work...

so it seems this is a software issue.

I then try this rom "Stock+_N6F26R-N6-by-tupac4u.zip" https://xdaforums.com/showpost.php?p=78172143&postcount=1348

this time, the "loud speaker" works, but the "in call speaker" still don't work...

well, better than nothing, so I keep using this rom.

then install magisk, xposed, root, all kinds of apk. but the "in call speaker" still not work.

then I discover, the phone call function works with bluetooth headset with mic, model is "Sony MDR-1000X"

then I discover, I can plugin the earbud with mic, the phone call works, I can hear and speak using the earbud with mic.

then I discover, I can plugin the earbud, but this earbud do not contain any mic, just a earbud, the phone still works, voice coming to earbud, and I speak to the phone mic.

today I discover, I have another bluetooth earbud, NO mic, model is "Havit I3S", I make a call, the havit I3S works for 5 seconds, and no sound...

then I switch to "loud speak", works. I then accidently switch to "phone" (the "in call speaker" I mention here), it works too. OMG........

then I disable the bluetooth function, reboot the phone, and make a normal call, the "in call speaker" and "loud speak" all works, OMG........

so now, both speaker works.

I do a full backup, and format the phone,

then install latest android 9, lineage-16.0-20190308-nightly-shamu-signed.zip with open_gapps-arm-9.0-pico-20190308.zip

the "in call speaker" and "loud speak" all works, OMG........

I then wipe the phone and install the latest lineage-15.1-20190303-nightly-shamu-signed.zip with open_gapps-arm-8.1-pico-20190308.zip

the "in call speaker" and "loud speak" all works, OMG........

To Sum Up

if your nexus 6 speaker does not work, do this

1. download the above rom "Stock+_N6F26R-N6-by-tupac4u.zip" install it

2. connect your nexus 6 to a bluetooth speaker/headphone/earbud (I use one without mic, you can try with mic)

3. make a call, you should hear voice in the bluetooth speaker/headphone/earbud

4. switch to the "speaker" in your nexus 6 phone app, the voice should come from the "loud speaker" now.

5. switch to the "phone" in your nexus 6 phone app, the voice should come from the "in call speaker" now.

6. try to make a full backup in twrp-3.2.3-0-shamu.img recovery https://dl.twrp.me/shamu/

7. wipe the phone, install your favour rom, try do a normal call without the bluetooth speaker/headphone/earbud, it should work now.