Jolla Phone Pre-order campaign has started

Even the SoC is not listed in the specs yet
But since the hardware is Jolla’s, they can enable VoLTE support, as they did with Jolla C2 a year ago (see [Release notes] Tampella 5.0.0.43 for Jolla C2)

Yes, it depends on the carrier
Those in Germany and France are usually stricter, while networks are generally fine in Jolla’s homeland
I don’t think Jolla could realistically negotiate with every individual carrier