Phoning in the United States

Hello BarbaraS_339285 . You certainly can, but it will be horrendously expensive!! Please see the Price Guide p18&19. https://cdn.smarty.co.uk/files/SMARTY-Price-Guide.pdf. 

You would need to add credit in advance to pay for any such usage.

I would suggest using wifi where possible over there and, if necessary, purchase a local sim for calls.