Hi. I think i found a real "PERMANENT" solution. I had the same issue and it kept resetting my changes after each restart, thus lacking a permanent solution like most of the repliers. I am aware of both methods to disable handsfree audio as in
-disabling from sound settings
-disabling from devices and managers -> device properties -> services
Both of these methods resulted in resetting after each restart, forcing me to re-do it every time, which is a pain in the a.
However i think the solution i found is a more permanent fix. Follow these steps
1- open "Device Manager"
2- scroll down to "System Devices"
3- under that tab find your "device name" followed by "Hands-Free AG". Example "soundcore R50i Hands-Free AG"
4- right click and select "Disable". (Not uninstall or remove, because i suspect it might re-install itself after reconnecting)
5- finally doht be bothered by this ridicule anymore
This is the only solution that worked for me.
I have an external microphone that I use, and only use my Bluetooth headset for the headphones. Microsoft teams always switches to telephony mode and it every windows update it bricks my choice. Replying here so I can find it next windows update again.
I have a Sennheiser Accentum which has a button to switch to both modes, and with the above steps I no longer have Teams switch my headset making me press the button.