Area code 787 is a significant telephone area code in Puerto Rico.

Geographic Coverage: Area code 787 serves the eastern and northern parts of Puerto Rico, covering an area of 3425.37 square miles. It includes 176 non-unique postal area zip codes and encompasses major cities such as San Juan, Bayamón, Carolina, and Caguas. This coverage makes it a vital part of Puerto Rico's telecommunications infrastructure​​.

Time Zone: The 787 area code lies within the Atlantic Standard Time (AST) zone. This time zone alignment is important for the region's synchronization with standard timekeeping practices, particularly for international communications and travel​​.

Cities and Counties Served: In addition to the major cities mentioned, area code 787 covers a total of 81 cities and 74 counties in Puerto Rico. This includes San Juan County, Guaynabo County, Trujillo Alto County, Bayamon County, and Ponce County. The wide range of cities and counties covered underlines the area code's significance in connecting various parts of Puerto Rico​​.

In summary, area code 787 is essential for communication across a significant portion of Puerto Rico, encompassing key urban centers and a large number of counties. Its location within the Atlantic Standard Time zone and the extensive area it covers are crucial aspects of its role in the island's telecommunication network.