Area Code Atlas

NPA 443 overlays 410

Area code 443 was overlaid onto the 410 territory on July 1, 1997, due to rapid number exhaustion in the Baltimore and Eastern Shore regions. This overlay introduced ten-digit dialing for all local calls within the region.

NPA 667 to Overlay NPAs 410 and 443 (Maryland)

Rationing in NPAs 410, 443, and 667 (Maryland)

NPA Code 667 to Overlay NPA Code 410/443 (Maryland)

NPA 667 implemented as a third overlay for 410/443

Area code 667 was implemented on March 24, 2012, as a third overlay for the 410 and 443 region in eastern Maryland. The addition of 667 provided relief for number exhaustion in the Baltimore metropolitan area and Maryland's Eastern Shore, addressing the continued demand for new numbers in the region.

Projected need for a fourth area code in the 410/443/667 region

Based on projections as of 2022, a fourth area code is expected to be required in the 410/443/667 region by about 2030 due to continued growth and number exhaustion.