Area code 813

Area code 813 is the area code in the North American Numbering Plan for the city of Tampa, Florida, and surrounding areas such as Zephyrhills and Oldsmar.

Area code 813 covers all of Hillsborough County, the city of Oldsmar in Pinellas County, and the central portion of Pasco County. The eastern portion of Pasco County is in area code 352, while the western portion is in area code 727.

Area code 813 became Florida's second area code in 1953, when it was split from the state's original single numbering plan area with area code 305. The new number plan area stretched along the Gulf Coast from Pasco County to Collier County and included the cities of St. Petersburg, Sarasota, Fort Myers, and Lakeland.

On March 3, 1996, 13 counties south and east of Hillsborough County, from Manatee County to Collier County, split from the 813 numbering plan area after 43 years in the coverage area and were assigned area code 941.

Although the 1996 split was intended to be a long-term solution, within only two years, 813 was close to exhaustion again because of the rapid growth of telephone service in the Tampa Bay area and the proliferation of cell phones and pagers. The Florida Public Service Commission decided to assign area code 727 as another area code for the region. It was originally planned to be an overlay for the 813 territory. However, overlays were still a new concept, and the mixing of area codes in the same region, and the resulting requirement for ten-digit dialing, met considerable resistance.

...
Wikipedia