Our carrier is t mobile. We were able to make calls with no charge to the United States if we were using wifi calling
We have used Sharon for phones and her service is great
Also if you have wifi and a computer you can use Skype. My mother is 89 and does not have a computer. Before we were able to call on t mobile we signed up for a month of Skype that let us call from our computer to any land line in the states. If my memory is correct it was $2.99 for the month and easy to cancel. We could call as often and as long as we wanted.
This was the year before last so you would have to see if that service is still available.