If not; then this (from the community meeting thread) does not really make sense:
Mainly other establishment cause and registration procedure. But what i’m trying to say is that demanding “entirely different” is pointless here. Different enough is just that, enough. And those two things are entirely outside of VoLTE. Then there may be similar differences inside the IMS/VoLTE subsystem too.
Did you have a point with this line of arguments? In that case please spell it out.
That’s not something Jolla distributes. And furthermore, the chances your operator will care are basically nil, so any efforts would be completely in vain anyway.
How to reflash vendor binaries, not that i can imagine it helping, is already documented. And again; i can’t see the operator giving a crap unless they were wrong in a way that is relevant on Android too (and then caring only about that).