NumberingData
Methodology Download the data
Area code Verified Nov 1, 2026 · Source: NANPA

Area code 603 – New Hampshire

603 is one of the original area codes, in service across New Hampshire since 1947. 752 of its 786 number blocks are allocated – about 96% full. No carrier dominates: Consolidated 33.0%, Other CLEC / VoIP 20.5%, Verizon 15.8%. FTC complaints naming a 603 caller ID totalled 402 in the 33 days to 30 October 2026 (248th of 422 ranked codes).

State
New Hampshire
In service since
1947
Time zone
Eastern
Shares area with
No overlay

Who holds 603 number blocks

Share of the 752 assigned NXX blocks (95.7% of the 786 possible), across 49 carriers. This is share of number blocks, not of subscribers.

  • Consolidated33%
  • Other CLEC / VoIP26.1%
  • Windstream7.7%
  • T-Mobile7.3%
  • Verizon6%
  • AT&T6%
  • Comcast5.3%
  • Lumen5.1%
  • Onvoy0.8%
  • Charter0.8%
  • Peerless0.5%
  • Telnyx0.4%
  • Vonage0.3%
  • American Messaging0.3%
  • Bandwidth0.3%
  • TDS0.1%
  • Dish0.1%

Spam complaints naming 603

FTC Do Not Call complaints where the caller ID was a 603 number, 28 Sep – 30 Oct 2026 (33 days). Caller IDs on spam calls are frequently spoofed, so these are complaints about the code, not calls proven to originate in it.

402 complaints in 33 days
#248 of 422 ranked codes

Rate centers in 603

NANPA allocates number blocks to rate centers and records their names abbreviated to ten characters, so these are NANPA's codes rather than place names – CHAMPAURBN is Champaign-Urbana, NWYRCYZN01 is a New York City zone. We show them unchanged instead of guessing at the full names. Showing the largest 5 of 147.

MANCHESTER80
NASHUA58
CONCORD39
DERRY29
DOVER29

Timeline

  1. 1947 603 assigned in the original North American Numbering Plan.

More about 603

Separate pages for the questions that need their own answer: what time it is there, what the complaint data says, who holds the number blocks, and how the code compares with the one it shares its area with.

All prefixes Every one of the 752 assigned NXX blocks, with the holder of each Local time Zone, UTC offset, clock changes and a live clock Spam complaints How often the code appears in FTC complaints, and what to do Carriers Who holds the number blocks, and why that is not who serves them

Frequently asked about 603

What state is area code 603?

New Hampshire.

Is a call from 603 a scam?

Not by itself. 603 drew 402 FTC complaints in the 33 days to 30 October 2026, 248th of 422 ranked codes – mid-pack or lower. Spam callers spoof caller IDs, so the only useful check is the full number.

Which carrier owns 603 numbers?

Consolidated holds the largest share of assigned number blocks at 33.0%. The rest is spread across 3 other carriers. This is share of number blocks, not of subscribers – people keep their numbers when they switch carriers.

Do I need to dial 10 digits in 603?

Yes – ten digits for local calls in 603, because it shares its area with another code.

Sources and verification

NANPA dialing note for this code: “10D”. Reviewed by the data desk. Spotted an error? Request a correction.