I got this straight from the head of technical services at Verizon. There is a grace period until July, until then both dialing methods should work (although we tried to call the colmado down the block last night and had to use 809). After July you will have to dial 1-809 for cell phones and long distance, meaning that if your calling Santiago from Santo Domingo you'll need to dial 1-809, but if your calling within SD just 809. New numbers will get the 829 area code with the same 1 prefix rules. She said that they considered area codes by region, but that it would have been more difficult to change numbers than to just add new numbers on top of the old system. Get ready to see a blitz of informational advertising preparing people for the new system, their main concern being that volume and revenues will drop due to the confusion.