Brooklyn, NY, uses three area codes: 718, 347, and 929.

In the U.S. phone numbering system, area codes are assigned by state or region, and New York City has a high population density, making it difficult to manage with just one area code, so multiple area codes are used. Brooklyn, along with Queens, Staten Island, and the Bronx, has shared the 718 area code.

718 was the first area code assigned to the outer boroughs of New York City (Brooklyn, Queens, Bronx, Staten Island), created in 1984 when it was split from Manhattan's 212. As demand for new phone numbers increased over time, 347 was added as an overlay starting in 1999. An overlay means that a new area code is added to the same region as the existing area code, allowing addresses in Brooklyn to have either a 718 or 347 number. In 2011, 929 was added as the third overlay area code.

It's important to note that in Brooklyn, even if you are dialing within the same area code (718→718), you must dial the full 10-digit number (including the area code). Since 2001, New York City has mandated 10-digit dialing, meaning you must dial in the format '718-XXX-XXXX' even for local calls. If you only dial 7 digits, the call will not connect, so be cautious.

With the rise of internet-based phone services (VoIP), it has become common for area codes not to match actual residences. For example, someone living in Brooklyn might use a 212 (Manhattan) or 646 (Manhattan overlay) number. VoIP services like Google Voice, Magicjack, and Ooma allow users to choose their desired area code, making them popular among immigrants as a cost-saving measure.

When making international calls to Korea, you dial the U.S. country code 1, followed by Korea's country code 82, the area code (Seoul 2, dropping the leading 0), and then the phone number. For example, to call Seoul 02-XXX-XXXX, you would dial 011-82-2-XXX-XXXX. Nowadays, free calls through internet messengers like KakaoTalk and Naver Line are mainstream, but using landline and cellular international calling plans or prepaid international calling cards can be more economical.