North American Numbers Source-cited · ownership disclosed
Area code
603
In service
United States · since 1947

New Hampshire (statewide)

Area code 603 is the single area code serving the entire U.S. state of New Hampshire. It is an original 1947 code with no split or overlay history.

The essentials Numbering data · NumberResearch · as of 2026-09-18
Place
New Hampshire (statewide)
Type
geographic
Status
in service
In service since
1947
Projected exhaust
2040 Q4

Status, dates and counts are read from NumberResearch (NANPA / CNAC / FCC records). Assignment records show initial assignees, not the carrier serving a number today.

A · Where it is

Where 603 is

The entire state of New Hampshire..

Communities served wholly or partly by 603:

ManchesterNashuaConcordPortsmouthDoverRochester
B · Relationships

How it relates to other codes

The codes 603 was split from, spawned, or shares its area with. A split divides the map and changes some numbers; an overlay shares the same ground and changes none — what's the difference?

What's changing. No overlay. Single statewide code. Exhaustion projected around 2032 (re-check NANPA).
C · History

How 603 got here

1947-10
Assigned as one of the original 86 North American area codes.
Source: Wikipedia
2021-10
Transitioned to mandatory 10-digit dialing after 988 was designated the Suicide & Crisis Lifeline.
Source: Wikipedia
D · Capacity

How full it is

Prefixes assigned
768
Prefixes available
32
Thousands-blocks assigned
3,109

Prefix-assignment counts describe allocation to carriers, not how many individual numbers are in use. Full technical records: NumberResearch ↗.

Compare 603 with another code →
Sources
Wikipedia ↗
Area code 603
NumberResearch.org ↗
Live status, dates, assignment counts and exhaust forecast — data as of 2026-09-18 (CC BY 4.0).

Place, relationships and history above are compiled by North American Numbers from the sources listed and last checked 2026-09-18. A check date is not an expert review — see how this is made. Flag an error.