Area code 603: New Hampshire
What is area code 603?
Area code 603 is a US state area code for New Hampshire, on Eastern Time. It has 752 prefixes in service across 147 rate centers, the largest being Manchester, Nashua and Concord. NANPA lists no overlay code for it. Local calls there take 10 digits. The code never shows a line is in service.
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See the phone add-onArea code 603 facts
| Location | New Hampshire, United States |
|---|---|
| Time zone | Eastern Time |
| Overlays | None |
| In service since | 1947, when the plan began |
| Local calls | 10 digits |
| Carrier | Not shown. An area code is where a number was issued; numbers port between carriers. Check line type |
In short: 603 is New Hampshire (Eastern Time). Format checks here are free and run in your browser; the current carrier and line type need a live lookup. Bulk phone number validator · Pro + Phone plan
Local time in area code 603
America/New_York
Prefixes in service
752 of 792 possible
147 rate centers
Which cities and towns use area code 603?
NANPA records each prefix against a rate center, the local billing area a number belongs to, usually named after its main town. These are the 603 rate centers with the most prefixes in service. 135 smaller ones aren't listed.
| Rate center | Prefixes |
|---|---|
| Manchester | 80 |
| Nashua | 58 |
| Concord | 39 |
| Derry | 29 |
| Dover | 29 |
| Portsmouth | 28 |
| Merrimack | 23 |
| Salem | 20 |
| Laconia | 19 |
| Keene | 17 |
| Rochester | 16 |
| Exeter | 15 |
Source: NANPA central office code assignments, file dated 10/17/2026. Each prefix holds up to 10,000 numbers.
How do I dial a 603 number?
NANPA's dialling plan for 603: local calls inside the code take 10 digits, toll calls 10 digits. From another area code, dial 1 first. From abroad, use +1. The examples use 555-0147, from a range reserved for fictional numbers.
| Local call inside 603 | 603-555-0147 |
|---|---|
| From another US or Canadian area code | 1-603-555-0147 |
| From outside North America | +1 603 555 0147 |
| E.164, for CRMs and SMS tools | +16035550147 |
When did area code 603 start?
Area code 603 is one of the original codes NANPA lists from 1947. It has no overlay, so every number in its area still starts with it.
Tools for 603 numbers
- Bulk phone number validator
Format, country and number type for every number in a CSV, with E.164 output.
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- Area code time zone
Local time for a list of numbers, with a callable-now flag.
- NPA-NXX lookup
Rate center and state for one prefix, a level below the area code.
- TCPA calling hours checker
Whether it's inside the federal 8 a.m. to 9 p.m. calling window there now.
Next step
A 603 number tells you where it was issued, not what it is now.
Mobiles, landlines and VoIP lines share area codes, and numbers move between carriers. A live line-type and carrier lookup on every number in your list says which is which, and that decides which calling and texting rules apply. It's in the phone add-on.
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Area code 603 questions
- What state is area code 603?
- Area code 603 is in New Hampshire, United States. Its largest rate centers by number of prefixes are Manchester, Nashua, Concord, Derry and Dover.
- What time zone is area code 603 in?
- Eastern Time.
- Does area code 603 have an overlay?
- Not as of NANPA's file dated 10/16/2026. Every number in its area uses 603.
- When did area code 603 start?
- Area code 603 is one of the original codes NANPA lists from 1947.
- Is a 603 number a cell phone or a landline?
- The area code can't tell you. In the US and Canada mobiles, landlines and VoIP lines share area codes and prefixes, and numbers move between carriers and line types. Only a live line-type lookup answers it for one number.
- How many phone numbers does area code 603 have?
- 752 of its 792 possible prefixes are in service, and each prefix holds up to 10,000 numbers. That counts prefixes assigned to carriers, not numbers in use.
- Does a valid format mean a 603 number is in service?
- No. A format check only says the digits fit the North American Numbering Plan and that 603 is an assigned code. It cannot tell whether the number is connected, who answers it or which carrier serves it today, because numbers are reassigned and ported. A live carrier lookup reports the current carrier and line type, but even that is not proof someone answers.
- Can I check a list of 603 numbers for free?
- Yes. Paste them in the list tab above or upload a CSV to the bulk phone number validator: format, E.164, country and the numbering-plan line type are free for every row, with no account. Live carrier and line-type lookups come with Pro + Phone at $49.99/mo (5,000 a month).
More area codes
603 is the only area code in New Hampshire. Browse every area code by state and province on the area code index.
Sources
Location, overlays, in-service date and dialling plan: NANPA NPA database, file dated 10/16/2026. Prefixes and rate centers: NANPA central office code assignments, 10/17/2026. Time zones mapped to the IANA time zone database. By the SimpleVerifier Team; how we build these pages.