Can/usa plan not working

[RemDD]

i have Canada/usa mobile plan with Iphone.
But when I go to US, my phone doesn't work as it should be. It says At&T on the phone but I could never get any messages or calls.  Do I have to select roaming manually or something? 

thanks. 

[hairbag1]

@RemDD 

assuming you have iPhone 8 or better...go in to your iPhone settings > Cellular > Cellular Data Options (Roaming ON)> Data Roaming enabled Voice & Data 5G On or LTE.      If AT&T fails, try to manually select T-Mobile.

These are settings that my Iphone SE are set to and used to work when I was going to us. 

[colleeno]

@RemDD 

Yes, you have to turn on Data Roaming. Your phone should automatically connect to T-Mobile, AT&T or Verizon. If it doesn’t, reboot your phone.

If you get a text message from PM about buying a roaming add-on, ignore it. It is sent when crossing the border whether you already have a roaming plan or not. 

[softech]

@RemDD 

which model of iPhone?  iPhone 8 and above should work

and your mobile data works?  Make sure you turn on Mobile Roaming Data on your phone.

and try different US networks.  Manually connect and try T-Mobile and Verizon as well. Your voice should work with that.