Telephone numbers in the Dominican Republic use area code 809 with 829 and 849 as overlay codes. Telecommunications in the Dominican Republic use the North American Numbering Plan (NANP) country code, 1, followed by the area code in the same form as an internal area code in other NANP countries, such as the US and Canada.
When in the Dominican Republic, the 3-digit area code followed by the 7-digit phone number must be dialed. When calling the Dominican Republic from the United States or Canada, this must be prefixed by the digit "1". From other countries the international prefix used in the originating country must be dialled before the "1".
Area code 809 was created on January 1, 1958. Initially, the 809 area-code was used for all of the Caribbean, with the exception of Cuba, Haiti, Aruba, the Netherlands Antilles, and the French West Indies. During the mid-1990s (March 1, 1996), Area Code 809 was split and eventually just assigned to the Dominican Republic. Following the departure of Saint Vincent and the Grenadines from 809 in 1999, no other countries use the legacy 809 area code. Today, Area Code 809 and its overlay area codes, 829 and 849, are used solely for the Dominican Republic.
Area Code 829 was added to local telephony as an overlay code, initially optional in July 2005 and later mandatory in November 2005. The new telephony rules were almost wholly due to the explosive growth of cellular communication in the Dominican Republic, starting in the mid-1990s with telephone prepaid-cards, and growing incredibly through the early 2000s with the launch of two new cell-phone carriers, Orange and Centennial, in addition to the preexisting CODETEL and TRICOM. Besides, the reason for this newly placed dual area code system is because it is estimated a standard 7-digit area code could hold around 7.8 million number combinations, and currently there are around 1.6 million land-based lines and 4.2 million cellular phones. Thus it was decided to attach another area-code to this country, because of the extensive growth and threat of number depletion.