So... I'm in Canada, and here's the fun part: I took a video of the network performance and all. Granted, I'm next to a window but it seems to consistently perform very, VERY well in places where the signal readings are horrible.
Watch this video on Streamable.
streamable.com
And yes, VoLTE and wifi calling work (had to ring up the helpline to get it to work, but it worked).
There's no way of knowing exactly what tech the networks here use (my phone isn't rooted) but it does show you that it's using 4xCA. The other time, I managed to hit 120 Mbps on similarly poor signal levels. And in case it wasn't apparent, I managed to hit ~70Mbps (upload was poor).
My package plan doesn't permit me to go beyond 250Mbps (just another stupid Canadian limitation - they're already very high, and if you pay more, you get almost uncapped speeds). Oh, and I'm on 4G.
Just goes to show what networks can achieve if they actually have a good focus on them (of course, it's probably 20x more expensive in Canada). Jazz is probably the only network with data that is largely usable as far as speeds are concerned in multiple places, but horrible for calls. Zong has picked up their performance as well and you can average around 20Mbps in multiple places via 2xCA. But the experience is consistent here.
I've read Rogers doesn't give you speeds anywhere near Bell nor Telus (and Bell and Telus both share antennas but have different backends, so the coverage between the two is nearly identical except in some cities or so). But they call them Robelus (cartel, and daylight robbery with prices).