Area Code Atlas

NPA 603 assigned as original area code

Area code 603 was assigned in October 1947 as one of the original North American area codes, covering the entire state of New Hampshire.

Extraordinary NPA-Specific Jeopardy Conservation Procedures Announced for 603 NPA (New Hampshire)

Overlay relief planned for area code 603

Area code 603 was projected to near exhaustion by 2013, prompting plans for a second area code to be activated as a statewide overlay complex. However, changes in number allocation policies and reclamation of unused numbers delayed the exhaustion to at least 2032.

Order requiring reclamation of numbers in 603

Order No 25,210 was issued on April 4, 2011, requiring the reclamation of numbers in area code 603 to address projected exhaustion and delay the need for area code relief.

Ten-digit dialing becomes mandatory in 603

Area code 603 transitioned to mandatory ten-digit dialing on October 24, 2021, due to the nationwide designation of 988 as the code for the Suicide and Crisis Lifeline, which conflicted with existing seven-digit dialing in the area.