{{Short description|Telephone area code for all of New Hampshire}} {{Use American English|date=February 2026}} {{Use mdy dates|cs1-dates=y|date=January 2026}} thumb|right|upright|Numbering plan area 603 in a 1956 map, comprising the entire state '''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.<ref>{{cite web|title=New Hampshire Public Utilities Commission |url=http://www.puc.nh.gov/Regulatory/Docketbk/2010/10-211.htm |publisher=New Hampshire Public Utilities Commission |access-date=November 20, 2010 |archive-url=https://web.archive.org/web/20110929085914/http://www.puc.nh.gov/Regulatory/Docketbk/2010/10-211.htm |archive-date=September 29, 2011 |url-status=dead}}</ref> 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.<ref>{{cite web|last=Brooks |first=Dave |title=Area code 603 will reign supreme thanks to technology |url=https://www.concordmonitor.com/area-code-603-2196133 |publisher=The Concord Monitor |date=May 18, 2016 |access-date=March 17, 2019}}</ref>
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.<ref name="pl556">{{cite web |title=Transition to 10-digit dialing (for 988 as 3-digit access to National Suicide Prevention Hotline) |url=https://www.nanpa.com/sites/default/files/planning_letters/PL-556.pdf |publisher=NANPA |date=2021-01-08 |access-date=2026-01-04 }}</ref>
==References== {{Reflist}}
==External links== {{Area code footer|Map=NH}} * [http://www.nashuatelegraph.com/news/local-news/2010/12/06/603-can-stay-single-for-a-few-more-years/ December 2010 newspaper article about then-uncertain future of 603]
{{Area code box |State = NH |This = 603 |N = 819/468/873 |S = 351/978, 413 |E = 207 |W = 802 |S1= MA |S2= ME |S3= QC |S4= VT }} {{Area code list}}
603 603 Category:Telecommunications-related introductions in 1947