In reply to a post by xela:

I use them already for my voip. actually, the thing that spurred this query was my parents’ irrational attachment to their landline, and me wondering whether ‘HD audio’ might be the thing that encouraged them to switch to VoIP. (Answer: not yet.)

….. and that’s the thing, it’s not, I suspect, call quality that is their stumbling block, it is the fear of change in technology.
High quality voice calls have been available via ISDN for years, but people don’t use them.

Yeah, partly true.

They also have a nice beocom 6000, which they don’t want to replace. I trialled a voip adapter years ago and wasn’t overly impressed with the results - sound quality and echo were issues.

I was kinda hoping that a new native voip solution might offer some benefit, like sound quality. Instead, it feels like the best I can do is hope that voip won’t be any worse than their current set up.

In reply to a post by xela:

Thanks for this - and all the other comments in this thread.

The only time I’ve noticed ‘HD audio’ is on FaceTime Audio calls, and it is a pleasant step up from standard telephone audio quality, so would be nice if A&A supported it at some point.

Unless you control both endpoints (as Apple do with FaceTime) then practically it is quite difficult to get full end-to-end support for HD voice as the not only do the codec settings for both endpoints need to match, the codec priority order does too.

Neither service providers or upstream carriers like transcoding as it is computational intensive and adds cost and complexity.

All in all it’s rather hit and miss on an interconnected public network, even with full SIP support otherwise in place.

I'm not sure this is an option due to the age of the handset, but you might be able to pair it to a DECT base station that does the SIP and avoid the conversion process that might be responsible for the echo. As nice as the handset might be it's still going to be an old DECT standard and there will be a limit on quality.