Area code 603 is the sole

area code A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, rea ...

for the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...

New Hampshire New Hampshire is a U.S. state, state in the New England region of the northeastern United States. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec t ...

in the

North American Numbering Plan The North American Numbering Plan (NANP) is a telephone numbering plan for twenty-five regions in twenty countries, primarily in North America and the Caribbean. This group is historically known as World Zone 1 and has the international callin ...

(NANP). It was created as one of the original 86 numbering plan areas in October 1947. In 2011, area code 603 was said to be nearing exhaustion and a second area code for New Hampshire was expected to be activated by 2013 as a statewide

overlay plan Overlay may refer to: Computers *Overlay network, a computer network which is built on top of another network *Hardware overlay, one type of video overlay that uses memory dedicated to the application *Another term for exec, replacing one process ...

. As a result of changes in allocation policies and a reclamation of a large block of previously allocated telephone numbers, including

number pooling Number pooling is a method of reallocating telephony numbering space in the North American Numbering Plan, primarily in growth areas in the United States. Instead of allocating blocks of ten thousand numbers to each carrier in each community, a bl ...

, the exhaustion time frame has been moved to at least 2032.

10-digit dialing

Prior to October 2021, area code 603 had telephone numbers assigned for the

central office code The North American Numbering Plan (NANP) is a telephone numbering plan for twenty-five regions in twenty countries, primarily in North America and the Caribbean. This group is historically known as World Zone 1 and has the international calling ...

988. In 2020, ''988'' was designated nationwide as a dialing code for the

National Suicide Prevention Lifeline The 988 Suicide & Crisis Lifeline (formerly known as the National Suicide Prevention Lifeline) is a United States-based suicide prevention Suicide prevention is a collection of efforts to reduce the risk of suicide. Suicide is often preven ...

, which created a conflict for exchanges that permit

seven-digit dialing Seven-digit dialing is a telephone dialing procedure customary in some territories of the North American Numbering Plan (NANP) for dialing telephone numbers in the same numbering plan area (NPA). NANP telephone numbers consist of ten digits, of wh ...

. This area code was therefore scheduled to transition to

ten-digit dialing Ten-digit dialing is a telephone dialing procedure in the countries and territories that are members of the North American Numbering Plan (NANP). It is the practice of including the area code of a telephone number when dialing to initiate a telep ...

by October 24, 2021.

Central office prefixes

Unless otherwise stated, most of the prefixes were introduced on or before February 4, 1994. Prefixes located in

Derry Derry, officially Londonderry (), is the second-largest city in Northern Ireland and the fifth-largest city on the island of Ireland. The name ''Derry'' is an anglicisation of the Old Irish name (modern Irish: ) meaning 'oak grove'. The ...

are also used in adjacent Londonderry. 976 is assigned to Concord, and requires dialling 1-603 first.

References

External links

List of exchanges from AreaCodeDownload.com, 603 Area Code

December 2010 newspaper article about then-uncertain future of 603
{{Area code list

603 __NOTOC__ Year 603 ( DCIII) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. The denomination 603 for this year has been used since the early medieval period, when the Anno Domini calendar era ...

Telecommunications-related introductions in 1947