[lxgr]

Opus provides excellent voice quality at 10 kbps (less than 1/6th of what PCM uses at 8 kHz), at a latency of 26.5 ms, so it's definitely not a technical problem for HFP either.

There's always the risk of unknown patent claims, but the same is true for any other codec not older than 15 or so years.

[dgrcode]

I actually didn't know about Opus, but having read a bit about it, how aren't we using that codec for all things audio? It's open source, has good platform support, quality seems to similar to AAC, it could be used for HPF. What's stopping the adoption of Opus in Bluetooth standards?

[lxgr]

Supposedly Google's Pixel Buds support it!

I can only suspect why it's still so rare, but my guess would be either a fear of unknown patent claims, a lack of readily available hardware implementations, or a combination of both.

[dgrcode]

I have the pixel buds A-series, and using my pixel 7a I can feel the quality going down when on a call. It might be just the latest buds, or my pixel 7a not supporting the codec, or the HFP not being set to use it ¯\_(ツ)_/¯