When we were in the DR back in July, we had T-Mobile as our US carrier. I was hoping to be able to use the international data for Google Maps and Navigation. As has been stated, T-Mobile's Data Coverage partner in the DR is VIVA. We were able to have unlimited text and make calls to the US for 20 cents per minute. The data is unlimited, but it is SLOW; so slow that I went ahead and bought a SIM card from Orange and loaded it with minutes, texts, and 1GB of data in order to be able to stay connected, whatsapp, and navigate. If you are looking to be able to facebook, twitter, email, navigate, etc., I don't think it's worth it. If you are just looking to text all the time and receive and make phone calls when needed (albeit expensive), then T-Mobile will work for you. I hope this helps.