The 603 area code is located in the state of New Hampshire, and according to Intelius data, covers roughly 809,552 phone numbers and 1,153,225 listings across 756 prefixes.
This is a General Purpose Code, in service since January 1, 1947.
Local and long-distance calls within area code 603 both require 10 digits dialing.
Have you received a call from a number with a 603 area code? Figure out who is calling you by performing a reverse phone lookup search. Intelius can provide you with a phone report that includes (when available) original line type and carrier, the number owner’s name, last known address and past addresses, age, possible relatives, and more.
| County Population (2025) | 433,415 |
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| County Population (2025) | 324,077 |
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| County Population (2025) | 135,043 |
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