Cell service usa

[Bill75]

I just upgraded from 3g to 4g and now travelling in usa.i have an add package that includes talk,text and data.i can send and receive texts cut cannot send or receive phone calls on my andriod samsung phone.i get a message disconnect on the network.do i have to upgrade to 4g sim card for talk service to work

[HALIMACS]

@Bill75 

Is your device VoLTE enabled?

If not, can it be switched down to 2G in the Network Connections?

Calling in the US can be problematic with Public Mobile given the decommissioning of the 3G network in the USA some time ago.