Last year I had a problem when traveling to the US with my Pixel 3a: I didn't have any network (no data, no call, nothing). Upon contacting O2 they said they needed to enable Wifi and 4G calling, but even after that, it never worked, even though my phone said 4G calling was enabled and the Pixel 3a was on the list of supported devices on O2's website.
I am about to travel to the US once again and I'd like roaming to work this time. I now have an iPhone 15 Pro. I can see that (1) in Settings > Mobile Service, Wifi Calling is enabled, and (2) in Settings > Mobile Service > Mobile Data Options > Voice & Data is set to 5G Auto (and I can switch it to 5G On or 4G).
What makes me fear that it still won't work is that when I go on the MyO2 app, in Support > International and roaming > Traveling to the USA, when I input my IMEI in Step 2, it says "This number is not recognized, please double check the digits you have entered are correct and try again".
Note: I bought this iPhone 15 Pro from the US, so it's a US version (no SIM, only eSIM, I had to go to an O2 store to get my SIM changed into an eSIM when I got it). Could it be the reason why it doesn't accept the IMEI?
