best thing to do is take an unlocked GSM fone from US to DR and activate it with
www.orange.com.do it's super easy and real cheap. you can use fones from T-Mobile, ATTWS GSM, Cingular GSM.
and if you want to call back to the US, the long distance is included in the regular mins...they don't charge extra for calling the US....
let me know if you need a fone, i have a slightly used nokia 3595 that you can use over there, i'd be willing to sell it to you...