The Service Providers in the USA have started sunsetting the 2G/3G network and shifting to the new generation of VoLTE technology, which means that the normal voice calls will not work due to the network technology change. AT&T USA has shut down their 2G/3G network in early 2022, T-Mobile USA has shut down its 3G with effect from 1st July 2022. However T Mobile 2G network is still on.
If you have a VoLTE compatible device you can still make voice calls and in order to do so you will have to follow the steps below to enable VoLTE on your device if it is not enabled automatically.
If you do not have a VoLTE compatible device then you will have to manually search for T-Mobile USA network and connect to it to make and receive calls. If you still chose to be on AT&T network then you can keep connected using App based calls, Data and SMS. If you are a prepaid customer and you are not able to find/log into any network(low coverage area), then you need to connect to a wifi, and subscribe to any of the Jawasak world packages, to enable data roaming on your number.
Standard roaming rates in the USA are applied. Roaming Abroad

What devices support VoLTE?

• Apple iPhone 8 and newer models
• Galaxy S Series (S8 / S8+ and newer models) including Unlocked models from Samsung.
• Galaxy Note Series (Note 8 and newer models) including Unlocked models from Samsung.
• Galaxy A Series (A10, A20, A32, A50, etc.) including Unlocked models from Samsung.
• LG G Series (G7 and newer models)
• Google Pixel 3 and newer models
• One Plus 7 Pro 5G and newer models

How do I turn on VoLTE?

Depending on the device, VoLTE will be in one of the following locations:

• Settings > Connections or Network & Internet > Voice Networks. Set the VoLTE toggle to On.
• Settings > Connections or Network & Internet > Mobile Networks. Set the VoLTE toggle to On.
• For Devices supporting 5G, VoLTE is automatically enabled as it is required for 5G.

• iOS 13: Settings > Cellular > Cellular Data Options > Voice & Data > LTE, VoLTE On
• iOS 14: Settings > Cellular > Cellular Data Options > Voice & Data > Set VoLTE On
• iOS 15: VoLTE is automatically enabled and the toggle is no longer shown.