Comment by kube-system 2 days ago
Carriers in the US restricted the phones people used in the 00s and early 10s, back when there were short model whitelists, CDMA networks, and radios with only a few bands… but not so much today. Global market GSM phones activate pretty much on any US carrier just fine today.
2/3g deprecation and VoLTE is precisely because US carriers are pushing forward with new tech.
I know there are phones that work on ATT that are not on that list.
Regardless, my point is that the situation has vastly changed over the past 20 years. It wasn't that long ago that you could walk into carrier's store in the US and literally every phone that was allowed on the network was on the shelf.
There were no activation for GSM phones. You insert a whitelisted SIM and the phone would just register(login) to the network. The network doesn't care. Phone might care, but it's processed instantly on the modem. It was Apple that added online "activation" gimmick to it.
"CDMA" networks built on proprietary Qualcomm cdma2000 standards used its equivalent of eSIM, and that was why it required special trusted phones for OTA programming. It was also used by Verizon which IIUC had better coverage than others so lots of people would have had memories of having to go through something akin to Apple activation.
As of 2025 both AT&T and Verizon (plus, as a downstream their MVNOs) have a whitelist of allowed phone models and block connection of other phones even if they're compatible with the network.
See https://www.att.com/scmsassets/support/wireless/devices-work...
To be whitelisted, the phones need to go through onerous testing process that goes way beyond just checking for network compatibility.