Calls to USA, Canada, PR are charged as local off-network calls.
The provider whom you should chose depends on whether you want pay-as-you-go prepaid, flex, postpaid, etc. Foe pay-as-you-go prepaid, Viva is the cheapest. For postpaid, it's a close call between Orange and Claro. Claro has more extensive 3G network but EDGE data speed suck big (about a speed of 36.6k dialup). Orange is catching up with 3G coverage and its EDGE data speed (for use with non-3G devices) is the best in the DR and comparable to the slowest DSL connection. Viva's data services suck BIG, speed is virtually zero at the peak times of day and comparable to Claro's EDGE speed (which is bad) in off-peak times.
The best rates you can get with Business plans on Orange, but for that you have to have your company. No company will offer you fully open (postpaid) plans. They will allow you to sign up for flex plans (prepaid/postpaid hybrid) where you prepay the minutes plan at a slight (about 5%) rate disadvantage to the fully open postpaid plan for the same number of minutes. After you use up your minutes you enter scratch cards but your minutes will be charged at the plan rate (e.g. if you get 60 minutes for 300 pesos, after you use up your minutes when you enter 100 pesos scratch card your minutes will cost the same 5 pesos per minute, etc.). In the DR you get free incoming calls and are not penalized to go over your minutes. In many cases the over-the-plan minutes are actually slightly cheaper than in-plan minutes.
The flex hybrid plans and postpaid plans require a contract of 12 or 18 months, but give you 30-50% cheaper calling than pay-as-you-go prepaid.
The pay-as-you-go minutes are at about 10-11 pesos per minute on Orange and Claro, and about 7.50 pesos (recently raised) on Viva.
On Claro pay-as-you-go you get 1 free favorite number (setup fee 50 pesos) and you can call up to 5 minutes per call free. then you can hang up and redial. You also get one favorite number for free SMS message-sending, but only within Claro network (no USA numbers).
You can get data plans both prepaid and postpaid, and they cost the same. Many prepaid data plans (e.g. Blackberry) can be gotten at day/week/two-week/monthly package. Claro has APN open on all prepaid Blackberry plans and does not limit data usage on APN so you will not have 3G speeds reduced. On postpaid plans it limits the data usage to 500MB per months at 3G speeds and after that the speed is reduced. Orange does not have APN open on prepaid plans, only on postpaid. It has an unofficial policy (at the moment) that it does not reduce 3G speed regardless of your data usage.
You can get Iphone plans and other smartphone plans in both Claro and Orange. But if you want smartphone (non-BB plan) I suggest you get Blackberry Social prepaid on Claro, costs RD$750 per month with taxes, because it has an open APN and can be used in any smartphone and even tethered with laptop. See here:
http://www.dr1.com/forums/living/115959-trick-cheap-3g-internet-claro.html and
http://www.dr1.com/forums/east-coas...an-cell-number-internet-without-contract.html