Miami-Dade County and the Florida Keys area in Monroe County, Florida have been using area code 305 for many years. Back in 1998, NANPA added NPA 786 as the relief method for NPA 305, but only for Miami-Dade County. The method is called “concentrated overlay”. The Florida Keys area (Key Largo, Marathon, Islamorada, Key West, etc) have continued using area code 305 only. However, in August 2001 NANPA introduced a permissive dialing period in the area in preparation for a future expansion of overlay complex 305/786 for Monroe County’s Florida Keys. During the permissive dialing period people can dial local calls using both 7 and 10 digit dialing, but are encouraged to use the latter.
On July 18, 2014 NANPA finally approved the expansion. Area code 786 will serve the aforementioned Florida communities starting June 1, 2015. 10 digit dialing for local calls becomes mandatory on April 18, 2015.
- August 1, 2001 – start of 7/10 digit permissive dialing period
- April 18, 2015 – end of permissive dialing
- June 1, 2015 – area code 786 activated for the portion of Monroe County served by area code 305
See official NANPA announcement and area code map (PDF document)