Area Code 603

About Area Code 603

Area code 603 is a geographic telephone area code assigned to Manchester, New Hampshire. It operates in the Eastern time zone and was first introduced in 1947. Original NANP code. State-wide New Hampshire.

Within New Hampshire, area code 603 is the only active area code, covering the entire state. The state's 1,402,052-person population (2023 Census Bureau estimate) is served by a combined 1 active code, with 603 primarily responsible for the Manchester region. New Hampshire's state capital is Concord, and its largest city is Manchester.

When you receive a call from a 603 number on your Caller ID, the call originated from a phone number assigned to the 603 area code — but be aware that Local Number Portability (in effect since 2003) means the caller could be physically located anywhere in the US or Canada. Area code 603 only confirms where the number was originally assigned.

Where is the 603 area code located?

Area code 603 is assigned to Manchester, New Hampshire, in the Eastern time zone. The state of New Hampshire uses 1 active area code, and 603 is the only one. Calls placed from the 603 area code originate from numbers assigned by NANPA — the North American Numbering Plan Administrator — and the 603 prefix appears on Caller ID for both landline and wireless calls placed from this region.

The Eastern time zone observes Daylight Saving Time, shifting from UTC-5 to UTC-4 in summer. The local time shown above is always current, so you can quickly check whether it's a reasonable hour to call back.

What cities and counties use the 603 area code?

The 603 area code serves 15 notable cities, listed below in order of population. The largest city in the 603 territory is Manchester (115,644 residents in Hillsborough County).

• Manchester, NH — 115,644 residents (20.5% of 603 numbers)
• Nashua, NH — 91,322 residents (16.2% of 603 numbers)
• Concord, NH — 44,066 residents (7.8% of 603 numbers)
• Derry, NH — 34,317 residents (6.1% of 603 numbers)
• Dover, NH — 32,741 residents (5.8% of 603 numbers)
• Rochester, NH — 32,552 residents (5.8% of 603 numbers)
• Salem, NH — 30,142 residents (5.3% of 603 numbers)
• Merrimack, NH — 27,056 residents (4.8% of 603 numbers)
• Londonderry, NH — 26,177 residents (4.6% of 603 numbers)
• Hudson, NH — 25,395 residents (4.5% of 603 numbers)

Phone number format in area code 603

All phone numbers within area code 603 follow the standard North American 10-digit format:(603) NXX-XXXX. The NXX is the central office prefix (also called an "exchange") and XXXX is the subscriber line number. For long-distance calls within the NANP, dial 1 + 603 + NXX + XXXX. From outside North America, dial your country's international access code, then 1 (the NANP country code), then the 10-digit number.

If you need to verify whether a specific 603 number is wireless, landline, or VoIP, you can use our reverse phone lookup tool. Be aware that number portability means the area code no longer guarantees the caller's physical location — only where the number was first assigned.

History of area code 603

Original NANP code. State-wide New Hampshire.

The original 86 area codes were assigned by AT&T and Bell Labs in 1947 as part of the North American Numbering Plan. At the time, rotary-dial phones meant codes with lower digits (like 212 for NYC, 213 for LA, 312 for Chicago) were given to the largest cities because they took less time to dial. Today's area code assignments still reflect those early choices, even though touch-tone and cell phones made the original reason obsolete.

Is the 603 area code safe to answer?

Area code 603 itself is a normal geographic code with no elevated spam risk. That said, scammers can spoof any area code — including 603 — so if you don't recognize the full number, let it go to voicemail and verify the caller's identity before calling back.