Area code 603

Area code 603 is the sole telephone area code in the North American Numbering Plan (NANP) for the U.S. state of New Hampshire. It was assigned as one of the 86 original North American area codes in October 1947.

In 2011, area code 603 was projected to near exhaustion and a second area code for New Hampshire was expected to be activated by 2013 in a statewide overlay complex.^[1] As a result of changes in allocation policies, including number pooling, and a reclamation of a large block of previously allocated telephone numbers, the exhaustion time frame has been moved to at least 2032.^[2]

Prior to October 2021, area code 603 had telephone numbers assigned for the central office code 988. In 2020, 988 was designated nationwide as a dialing code for the Suicide and Crisis Lifeline, which created a conflict for exchanges that permit seven-digit dialing. This area code was therefore scheduled to transition to ten-digit dialing by October 24, 2021.^[3]