The dual area code system was added to local telephony in July 2005 and later mandatory in November 2005. (If you did not dial with area-code it would tell you to please dial again.) The new telephony rules were almost wholly due to the explosive growth of the cellular population in the Dominican Republic, starting in the mid 90's with telephone prepaid-cards being the main propulsion, and growing incredibly through the early 2000s with the launch of 2 new cell-phone carriers making the major-cellular provider count 4, nationwide. The 809 area-code, which used to be the default legacy area-code for many other Caribbean areas like Puerto Rico. In the mid 90's, was split and eventually just assigned to the Dominican Republic. Also, the reason for this newly placed dual area code system is that it is estimated the standard 7-digit area-code could hold around 9.5 million number combinations, and currently there are around 1.6M landbased lines and 4.2M cellular phones. Thus it was decided to attach another area-code to this country, because of the extensive growth and threat of number depletion.
When in the Dominican Republic, the full area code + seven digit phone number must be dialed. When calling to the Dominican Republic from anywhere in the United States or Canada, be sure to know first what area-code is for the number you're dialing, 829 or 809 (the latter being most prominent, having 99% of the numbers as of now.) Example: 1(809)|(829) + seven digit phone number.
