At first, VoLTE will be used to deliver "Rich Communications Services" (which look like something similar to what Voice over IP/Video over IP outfits offer today) rather than completely replacing narrowband voice. It will be awhile before Verizon is willing to commit to that, due in part to LTE outages in late 2011.
On the flip side is MetroPC, which has pushed VoLTE as hard as it could.
Then there's Sprint, which will stick to voice over 1x for the foreseeable future, but routes Direct Connect over IP. Sprint's latest DC incarnation seems quite similar to one facet of RCS over LTE.
I just killed all Sprint bands on my note 10 plus and immediately latched onto band 66 upon restart. Although the speed test initially spiked to around 11 Mbps it did quickly throttle back to about 5 Mbps.
Seems like the Pixel 4 XL LOVES to hold on to B41. Makes me wonder if the Pixel 2 XL actually supported HPUE.
It seems like the performance of the Pixel 4 XL > Pixel 2 XL.
Faster speeds, never falls to 3G, better radio performance overall!