Area code 603: where it is and who calls from it
Area code 603 is in New Hampshire.
New Hampshire (all)
| Where | New Hampshire |
|---|---|
| Time zone | Eastern Time ยท local time |
| In service since | 1947 |
| Overlay | No |
| Prefixes assigned | 752 of 792 possible (95%) |
Where 603 numbers started
Every prefix is assigned to a rate center, the local calling area it was set up in. These are the biggest in 603, with how many prefixes each has.
Plus 85 smaller rate centers.
Who holds 603 numbers
- Mobile carrier 26%
- Local phone company 34%
- Internet / business phone carrier 31%
- Phone company 9%
| Carrier | Type | Prefixes | Share |
|---|---|---|---|
| Consolidated Comm Of No. New England-nh | Local phone company | 246 | 33% |
| Bell Atlantic Mobile | Mobile carrier | 74 | 10% |
| Windstream (PAETEC) | Internet / business phone carrier | 58 | 8% |
| MCImetro (Verizon Business) | Internet / business phone carrier | 45 | 6% |
| Comcast | Internet / business phone carrier | 40 | 5% |
| T-Mobile (including Sprint) | Mobile carrier | 38 | 5% |
| UScellular | Mobile carrier | 37 | 5% |
| Level 3 (Lumen) | Internet / business phone carrier | 37 | 5% |
| AT&T Mobility | Mobile carrier | 34 | 5% |
| Freedom Ring Communications | Phone company | 32 | 4% |
Most prefixes are pooled: the 10,000 numbers in each are handed out in blocks of 1,000 to different carriers, and people can also take their numbers to another carrier. So the carrier shown is where the prefix started, not a guarantee about any one number.
States served: New Hampshire.
Got a call from 603?
An area code tells you where a number was first assigned, not where the caller is. People keep their numbers when they move, and scammers can fake any number. If you weren't expecting the call, let it go to voicemail.
If the call shows a 603 number that matches the first six digits of your own, that's often neighbor spoofing. Use the box above to check the full number.
Area code facts from the NANPA area code database (updated 10/06/2026); prefixes and carriers from NANPA's central office code records (updated 2026-10-10). Place description adapted from Wikipedia, CC BY-SA 4.0.