Well, my new Samsung A01, with a T-Mo SIM that handles 4G LTE data and Wifi calling, well, now I'm not getting any DATA plan. I get LTE data, for the VoLTE (*"HD Voice") calling, and my account lists that data usage as "whitelisted", but there's only a few other listings under the account for "data", from prior dates. (I just got the phone a few days ago.)
So, it seems like the 4G LTE bands that it uses (it's an "International" phone), are supported by T-Mobile, and it auto-created the right APN settings for it, those all match, but for some reason, I'm not getting usage of my 2GB of 4G LTE data per month. It just rolled into the next billing cycle, maybe something's up.
T-Mobile's pre-paid site, wouldn't accept any zip codes whatsoever, either, when either clicking on "Bring your own device", or "shop phones". Great web site guys.
And when I enter the IMEI to check compatibility, they claim that they don't recognize it.
I called customer support, and the guy had me go over a few things, reboot the phone, verify the APN settings. Yeah, all good.
Maybe this phone is "too new", it only came out a few months ago, and it's not in T-Mobile's system.