It seems a reasonable assumption that two different mobile networks in the UK (‘3’ and ‘EE’) have not both made changes at the same time that would render non-VoLTE calling inoperable on my two SFOS phones (yes, I know the XA2+ doesn’t do VoLTE on SFOS). Especially since there are no problems on other phone types (iPhone, Blackberry).
And, since @teleshoes can make non VoLTE calls on an X10 iii in the US, the obvious question is whether Jolla have made any changes to the phone stack in SFOS between .13 and .15 that could have caused an interaction problem between SFOS and these two UK networks?
Anyway, at least for now I will need to rely on my iPhone(s) for work and play, since I cannot rely on a phone (XA2+ which was my main daily driver) that can no longer make or receive phone calls. The X10 iii, with its disappearing sound, almost non-functional camera (unless you and your subject stay perfectly still), alarms that don’t go off, etc is simply not usable for me as a daily driver. 