The 603 area code covers Manchester, Nashua and 136 more places in New Hampshire.
Area code 603 is in New Hampshire, on Eastern Time. In the 603 area, phone numbers are given out most in Hillsborough County, then Rockingham and Grafton counties. It has been in service since 1947.
- Where
- 8 counties in New Hampshire, mostly Hillsborough County, Rockingham County and Grafton County
- Time zone
- Eastern Time
- In service since
- 1947, one of the original area codes
- Shares its area with
- No other area code
- Prefixes in use
- 752
- How to dial
- Local calls need all 10 digits: 603-555-0142.
Find out who called you from a 603 number.
Enter the full 10-digit number to see who it is listed to and the city and state on the listing. It is the same free check as our who called me lookup. To see only the caller ID name on the number, use our free CNAM lookup. To see whether it is a mobile, a landline or a VoIP line, use our free VoIP checker. To see which carrier a (603) number is on today, use our free carrier lookup.
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Manchester holds 11% of the phone prefixes in area code 603.
A prefix is the three digits after the area code, and NANPA assigns each one to a town. Counting the 752 prefixes in use shows where 603 numbers are actually given out.
- Manchester80 prefixes, 11%
- Nashua58 prefixes, 8%
- Concord39 prefixes, 5%
- Derry29 prefixes, 4%
- Dover29 prefixes, 4%
- Portsmouth28 prefixes, 4%
- Merrimack23 prefixes, 3%
- Salem20 prefixes, 3%
Also served: Laconia, Keene, Rochester and Exeter and 126 smaller places.
Consolidated Communications holds the most phone number prefixes in area code 603: 248 of 752.
NANPA, which runs the North American numbering plan, assigns each prefix (the three digits after the area code) to one carrier. Here is how the 752 prefixes in use in 603 divide between carriers; holders this page does not name are grouped as other carriers.
| Carrier | Prefixes | Share |
|---|---|---|
| Consolidated CommunicationsLandline company | 248 | 33% |
| PAETEC (Windstream)Windstream's business phone network | 58 | 8% |
| Comcast (Xfinity)Cable company's phone service | 40 | 5% |
| T-MobileMobile network | 38 | 5% |
| Level 3 (Lumen)Lumen's business and wholesale network | 37 | 5% |
| UScellularMobile network | 37 | 5% |
| 39 other carriers | 294 | 39% |
80% of these prefixes are pooled, which means the blocks of 1,000 numbers inside them can belong to other carriers. Any number can also have been moved to another carrier since, so this shows who holds the prefixes, not who serves a given number.
Want the carrier of one exact number? Our free carrier lookup checks it, because numbers move between carriers.
Source: NANPA central office code assignments, October 1, 2026.
603 has covered the same ground since 1947.
1947
603 is one of the original North American area codes.
A 603 number on your screen can still be a scam, because caller ID is easy to fake.
- Let an unknown call go to voicemail. A real caller leaves a message; a robocaller usually does not.
- Look the number up with the box above before you call back, because calling back tells a robocaller your line is live.
- Hang up on anyone who wants gift cards, crypto or a wire transfer, or asks you to read out a code that was just texted to you.
- Report unwanted robocalls at reportfraud.ftc.gov, or paste a suspicious message into our free scam checker.
The area codes closest to 603 are 802, 978 and 617.
This list measures the distance between the centres of each area, across state lines, and shows codes that share one area together.
These are the questions people ask most about area code 603.
Where is area code 603?
603 covers Manchester, Nashua, Concord and Derry and 134 more places in New Hampshire. In the 603 area, phone numbers are given out most in Hillsborough County, then Rockingham and Grafton counties.
What state is area code 603 in?
New Hampshire. 603 is a New Hampshire area code on Eastern Time.
What cities use area code 603?
The places holding the most 603 prefixes are Manchester, Nashua, Concord, Derry, Dover, Portsmouth, Merrimack and Salem, out of 138 places in all. The count comes from NANPA's prefix assignments as of October 1, 2026.
Which phone company owns area code 603?
No single phone company owns 603. NANPA's records show Consolidated Communications holds the most 603 prefixes, 248 of 752, followed by PAETEC (Windstream) and Comcast (Xfinity). Numbers move between carriers, so check one exact number with a carrier lookup.
What time zone is area code 603 in?
603 is on Eastern Time.
When did area code 603 start?
603 is one of the original North American area codes, in service since 1947.
How do I dial a 603 number?
Local calls need all 10 digits: 603-555-0142.
Is 603 a toll-free number?
No. 603 is a regular area code for Manchester and Nashua in New Hampshire, not a toll-free one. The toll-free codes in North America are 800, 833, 844, 855, 866, 877 and 888.
What area codes are near 603?
The closest are 802 (Burlington, Vermont), 978/351 (Lowell, Massachusetts), 617/857 (Boston, Massachusetts) and 781/339 (Waltham, Massachusetts), measured between the centres of each area.
Who called me from a 603 number?
Enter the full 10-digit number in the lookup above. It returns the listed owner where there is a public record, where the number is registered, and whether it is a mobile, a landline or a VoIP line.
Is area code 603 a scam?
603 is a real New Hampshire area code, so the code itself is not a warning sign. Scam callers fake local-looking numbers on purpose, so judge the call by what the caller asks for, and look the number up before calling back.
Put this lookup on your site: our free area code widget takes two lines of code and shows any US area code's state, time zone and local time.
Source: NANPA, the North American Numbering Plan Administrator: its area code database and prefix assignments, as of October 1, 2026.