International Call/Text - South America - NO SERVICE

International day pass or the Elite/premium plan, limits what you pay only for connecting to a non AT&T service provider in Latin America.

These roaming allowances do not permit, force, allow a connection, neither do they override local users or block service.   

   Connectivity is entirely between the local service provider and the capabilities of your phone. Since you were using an iPhone 12 which is a world phone, has every network connection possible, it is not your phone. That means it's the local service provider.   Either you are in a dead zone, they had an outage, or they're choosing to serve their own customers before serving a roaming phone.   We can't know, as you were using another provider.  Selecting a different service provider in settings may allow you to reconnect, as you have discovered. But that's still up to the local provider, not AT&T

Usually turning a phone off and back on again will allow a connection. Sometimes you have to reset network settings (general, reset, reset network setting.  This will erase any saved Wi-Fi passwords)

It doesn't matter where you roam you are at the mercy of a different service provider. All AT&T can do is limit what you pay for connecting to a different service provider rather than charging the high roaming rates.

If you think it might improve service, unlock your phone, or bring a compatible phone and use local service providers instead of roaming with AT&T.   Much of South America still has 2g and 3G service which is longer range than LTE

Well, you're missing your target by posting in the Internet forum.  😁

I'm moving this thread to the Wireless forum.

If this was moved, would I still see it here? Thanks! 

Actually, look up top  ⬆️