Prevent domestic roaming?

[Joe h]

i have t mobile and an iPhone 8+. Problem is whenever I’m on the fringe of the coverage zone, it wants to roam on AT&T, and the data becomes painfully slow. I have to keep switching airplane mode on and off to get it back on t mobile. I would rather the phone just lose service than connect to an AT&T tower. I tried to disable roaming in setting>cellular, but that seems to only affect international roaming.
[doublepost=1557541696][/doublepost]I found it.

 

[madeirabhoy]

must be an American thing as in Europe ive never seen a mobile switch carriers because of signal.

however surely you just go to settings, mobile data, network selection, and turn that from automatic to at&t