Area code 603 is the sole telephonearea code in theNorth American Numbering Plan (NANP) for theU.S. state ofNew Hampshire. It was assigned as one of the 86original 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 statewideoverlay complex.^[1] As a result of changes in allocation policies, includingnumber 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 thecentral office code 988. In 2020,988 was designated nationwide as a dialing code for theSuicide and Crisis Lifeline, which created a conflict for exchanges that permitseven-digit dialing. This area code was therefore scheduled to transition toten-digit dialing by October 24, 2021.^[3]

• "Area Code Maps".North American Numbering Plan Administrator.

• December 2010 newspaper article about then-uncertain future of 603

• Area codes in New Hampshire
• Area codes in the United States
• Telecommunications-related introductions in 1947

• Articles with short description
• Short description is different from Wikidata
• Use mdy dates from January 2026