alt Hacker NewsFor the major US carriers, since they shut down 3G, VoLTE is the only way calls work. Which meant that a non-VoLTE-but-4G-capable device can no longer make 911 calls.
I was using a Samsung S5 running LineageOS for a while with Google voice for calls, but the no 911 thing is one of the main reasons I finally moved to a different phone. The S5 supports VoLTE but only with stock firmware.
Auch, wasn't familiar with that, haven't been in the US for a while. At least around here (EU) is not enabled by default on phones you buy off the shelf. I'm not sure about phones bought from the carrier.