AT&T Roaming Error Message-How to Manually Connect to T-Mobile

What is Happening?

As AT&T is working on shutting down their 3G network, you will not have access to voice calling while connected to the AT&T network. You will receive this automated text message if you’ve tried to make a voice call.

Instructions for Switching Mobile Carrier to T-Mobile

You will be able to make voice calls by switching to the T-Mobile network by following the steps below for Apple and Samsung devices.

The links provided include screenshots of each step.

iOS

1. Settings
2. Cellular
3. Network Selection
4. The network Selection defaults to Automatic. Tap once on the toggle to change it to manual.
5. It normally takes a few seconds for the available networks to show up. Select T-Mobile.

https://osxdaily.com/2022/01/29/how-to-manually-select-carrier-network-on-iphone/

Android

1. Settings
2. Connections
3. Mobile Networks
   Note: If the device is running Android Lollipop, you will need to choose More Networks, then Mobile Networks

4. Network Operators
   Note: Some users may need to tap, Manually Select. The device will then scan for available networks.

5. Select T-Mobile

https://www.samsung.com/uk/support/mobile-devices/how-do-i-manually-select-a-network-on-my-samsung-galaxy-device/