I use two MVNO thats on ATT network (USA). Red Pocket for most stuff including my internet (tethered to computer) and a $40 per year Tracfone emergency account (BYOP=bring your own phone). Started getting the daily Tracfone messages that my old MOTO E2 phone will no longer work after Feb. Yea, its a 4G LTE phone and it does some sort VoLTE (voice over LTE) as VoLTE pops up at top screen when I turn it on. But its not "whitelisted" and ATT network is going to screen out phones that manufacturer didnt spend the money (paying ATT) to get whitelisted. Whatever their specs. they did finally block it.
I studied the ATT whitelist and got two used ATT network phones that are on the list. One is some Kyocera and other a Sonim XP5800. Heavier duty than your average burner phone. One cost me $25 and other $40. Hey its not that easy finding cheap phones that are whitelisted when everybody is scrambling at last minute. Tracfone still sent emails for a while but have stopped now. RedPocket didnt email me until last week in January. They seem real laid back about it. Even selling a non-whitelisted feature phone they say meets ATT standards??? So apparently the MVNOs have some leeway in the matter. Heard that Cricket was even banning some phones that are whitelisted by ATT. Greed knows no bounds.
So pretty sure I am safe far as Red Pocket goes. Heaven only knows about Tracfone. Its a $40 365 day plan so seriously if they want to ban my phone by end February, I will just forfeit remaining minutes/texts/data and call it a day. Not spending more money for an emergency car phone.
I live rural and ATT network really my only option. Too bad, Tmobile isnt whitelisting, they require VoLTE but say whatever works is ok by them. This IMEI whitelisting is so much bovine feces.
Oh you want shocking price, go look for phone called Punkt and one called Light. Punkt is whitelisted, dont think Light is, but for a basic feature phone, they are quite proud of them.
Oh want to mention the Kyocera is a full blown Android with insane amount apps included thanks to ATT that cant be removed short of rooting the phone. I found an app called Super Freez that supposed to keep apps inactive unless in use and another is a launcher called Discreet Launcher that only shows apps you want. Only want dialer and messaging, thats fine. Otherwise just wallpaper. Also blocks all those stupid notifications. Turned an annoying phone into something close to basic dumb phone. Even with Super Freez, doubt battery comes close to lasting like a true dumb phone. But I am not out and about much. Mostly use phone tethered to computer which keeps it charged.