It's more of an issue for carriers who don't sell Pixel devices, particularly in countries where the Pixel isn't sold officially (eg: New Zealand). So generally VoLTE, VoWiFi and sometimes even 5G too might not work. You can use a hack to get around that, but now Google has blocked that hack: https://news.ycombinator.com/item?id=45553764
Edit: Looks like there's an updated workaround now, but this is what I mean - it's really unacceptable that an essential feature like VoLTE - which is required to make phone calls - may not work depending on your carrier/region.
Actually I'm not sure it's reasonable to complain about a feature that you're informed won't work, on a phone that you're using in a region it's not meant to be in, doesn't work.
Yes, Pixels should probably be sold in all markets. But if you're explicitly circumventing that you shouldn't be surprised.
I disagree, because making phone calls is the most basic and core functionality of a phone, it's not just some random feature that you can simply dismiss, especially with many counties worldwide shutting down 3G networks - VoLTE is a necessity if want to make phone calls.
Google is the only major OEM (that I'm aware of) that has these deliberate draconian roadblocks to prevent VoLTE - an essential feature - from working. On OnePlus and Xiaomi devices for instance, you can always go into the engineering menu via the dialler and enable VoLTE on unsupported networks. Xiaomi even has an official code to disable carrier checks. Samsung takes it a step further and partnered with the GSMA[1] to enable VoLTE globally by default on all their Android 15+ phones. So I think it's fair to criticise Google for going in the opposite direction as other Android OEMs.
A phone bought in one region should be supposed to continue working when you travel to other regions - which people (in most parts of the world) do all the time.
And, indeed, my phones all do that. However, they don't all work with local sim cards, so something fishy is still going on, sometimes.
It's perfectly possible for VoLTE not to work in regions where no carrier provisioning information is available while foreign SIM cards work fine.
In theory a phone can just be provisioned by the network to use VoLTE, but in practice the spec allows for all kinds of incompatible configurations. Carriers and phone manufacturers won't just apply an untested configuration, and for good reason. Software upgrades have broken telecommunications from iPhones to Androids, sometimes edge cases such as calling 111/112/911/999 turn out not to work.
Falling back to 3G or even 2G on unknown networks in unsupported markets will get you voice calls, at least for the coming years.
Edit: Looks like there's an updated workaround now, but this is what I mean - it's really unacceptable that an essential feature like VoLTE - which is required to make phone calls - may not work depending on your carrier/region.