Canada + US Account: No network connection on iPhone in US

[Derrickr]

I have the Canada and US plan and am currently in the US but my iPhone is NOT connecting. It's very unstable. Barely connects and then remains disconnected for hours. What is the solution. Urgent please.

[Derrickr]

So far it looks like the manual selection of T-Mobile is working. I'll monitor for some more time and if this works then I'll accept this as the solution. Thanks.

[softech · Accepted solution]

@Derrickr 

Critical part to US roaming depends on T-Mobile/AT&T coverage and whether you can connect successfully onto either network.

If the phone is not connecting to T-Mobile/AT&T, change the Network Connection from Automatic to Manual and select and test both T-Mobile and AT&T and see which one you can connect.

If your issue is with data, make sure your Roaming Mobile data is enabled and you have disabled your mobile data limiter.  Also change your network mode to 4G (and don't try 5G until you can connect and works on 4G)

If your issue is with voice, make sure VoLTE is enabled on the device setting.  And if it does not work, try to change the Network to T-Mobile ONLY, and change  Preferred Network Type or Network Mode to 2G and see if the calls go through.
Also, you can download VoIP app TextNow as a workaround to make calls and text if you have Wifi or if your roaming has data component and data  is working