Can't make or receive calls while I'm in the US but can sms,Messenger and email okay

[NeilB]

Thanks found it

[softech · Accepted solution]

@NeilB 

the option could have been hidden, but on Android, check Settings>Connections>Mobile Network.  Or on iPhone, Settings>Cellular> Cellular data> Voice & data

[NeilB]

How do I check if volte is enabled, where is it in my settings?

[softech]

@NeilB 

so, your roaming data works?

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

With your voice issues, 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