Prior to March 1, 1996, Puerto Rico was one of many Caribbean islands served by area code 809.
On that date Puerto Rico was assigned the new area code 787.
Within only four years, 787 was already on the brink of exhaustion due to the proliferation of cell phones and dial-up Internet connections.
To solve the problem, 787 was overlaid with area code 939 in or about September 2001, with ten-digit dialing required for all calls.
This article related to a telephone area code is a stub.