Hello,
The Dominican Republic uses the North American Numbering Plan. This means that calls to and from this country work just like US state to state calls. On the other hand, when traveling overseas with your US cell phone nothing changes in how your US friends call you – they dial the same number.
So: to call a US number from DR dial 1 ??? ??? ????.
There are 3 active area codes in the Dominican Rep: 809, 829 and 849. Since these codes overlay, 10 digit dialing is required. Example: 809 ??? ????. This is for local calls. I’m not sure if all calls in the DR are considered local calls. If not, for long distance calls you would have to add 1 to the number.
People from the DR would dial your complete US number: 1 ??? ??? ????.