T-Mobile offers unlimited free text and data in over 100 countries, including DR. Voice calls are $.20 a minute, about the same as a prepaid call from Claro, etc. WhatsApp calls free with the data. I used it exclusively last trip, a few months. The speed is slower in some places. Your phone picks up whatever carrier is nearby, and Claro must be their preferred towers because that’s what I had 90% of the time. When Claro went down, Altice would take over, and it was lightning fast, in comparison. In SD I had LTE, where we live I got 2-3G.
I think I just read that the cost for calls is going up to $.25 soon