I have used thse guys a ton over the years. Usually pretty good, but once in a while their system gets whacky.
http://www.nobelcom.com/nobelcom/jsp...FFN=1058049641
I've also tried caribone and they give me a bunch of minutes but it seems like every few minutes the connection gets real dicey. I wind up telling the people on the other end to just wait a minute and it will clear up. I am going back to nobelcom. . . . .
If you call the same people in the DR, and you call a lot, better off getting them DSL and a Vonage or similar VOIP phone. I am looking into getting a second number just for that. 1500 pesos per month plus 15 bucks for vonage sure beats paying a few hundred in calling cards!!! Plus if they have a computer you can chat, webcam etc.