It's particularly ridiculous that you're complaining about digital lines having a low frequency range.
Whatever you remember, it isn't reality.
I think for a lot of us later Gen-X and older Millennials, as we age our ears don't work as well as they used to. Especially those of us like me that didn't heed good ear protection. I can't speak for everyone, but I suspect if today me tried to talk to someone on a landline back in the early 90s it'd still suck as bad as it feels like it does with cellphones today. We get more range with our phones now but our ears have a harder time processing it.
Just a thought.
On top of that, I think many remember "landline quality" in terms of a relative comparison with potato-quality early mobile phone codecs, analog mobile phones, heavily compressed discounted long-distance calling circuits etc. of the time.
Yes, landlines were better than any of that, but it doesn't mean that they were actually good by today's standards.
Which? Whatsapp call sound shit. Mobile phone calls sound shit.
I did Mumble to get some acceptable quality.
Not for me; it's way better than any landline I've ever used.
Not sure what we're doing differently – are you sure it's not your or the other party's speaker or microphone?
> Mobile phone calls sound shit.
Not for me either, at least not when EVS ("HD voice") is used, which is more often than not these days when calling friends/family.
2G connections used to sound quite bad, but since 4G, the limiting factor for me has been the other side being on a landline (mostly for business calls), which usually doesn't support wideband audio.
The default codec configuration for Mumble is opus.