Re:Norway switches off FM radio, but a station is defying go...
by Rjevski on Friday December 15, 2017 @09:52PM
(#15937140)
VoLTE is only between your phone and your carrier; if you're calling someone on another carrier as far as I know it still goes over legacy garbage with a shitty codec (or worse, an analog link, with in-band signaling).
Basically there aren't many phone calls over non LTE based services. Especially since VoLTE can be used over WLAN via Wlan calling techniques. (the latter isn't supported in all networks.)