I use Blue Parrot B450XT Headset and it do not answer the call with it's button. Volume does not work as well. Is it issue with UT or Volla?
Will appreciate any suggestion to solve this issue.

@Keneda said in AT&T SIM does not work in the US:

For now your best option to be able to call in the US with a 4G device is to use SIP call, go to ubports north american telegramm group (ask from there https://t.me/ubports) for more info and to get the SIP app to install.

Session Initiation Protocol work when the phone is connected to the Internet. How I connect to the Internet without connection to local provider.
At home I have my computer with VoIP.
I have Android phone with 4G and it is work perfectly with AT&T SIM.

Here is a link from another thread https://ubports.com/en/blog/ubports-news-1/post/first-steps-in-volte-support-for-ubuntu-touch-3768
Looks like this issue were addressed.
Wondering, when we can get it work?
May be I can help on it some how?

I’ve got my Volla Phone 23X in the US. Insert SIM card by AT&T. I use this SIM in my iPhone for several years after unlocking.
Getting message in Network “SIM 1 Unknown”. In cellular settings -> Carrier and APN -> Carrier is inactive and indicates “None”.
Us I red this is VoLTE issue which is not supported by Ubuntu Touch. And in 2021 ubports started investigate it.
Some one have a Volla Phone working in the US?