339 Area Code: Boston's Suburbs & the Route 128 Corridor

The 339 area code is the overlay that shares Boston's inner suburbs with 781 — the ring of cities and towns around Boston, strung along the famous Route 128 technology corridor. From Waltham and Woburn to Lynn, Quincy, and Dedham, 339 covers the same suburban belt as 781, added in 2001 to keep the fast-growing region supplied with numbers.

This guide covers where the 339 area code is, the Route 128 tech corridor that defines it, how 339 overlaid 781, how the two codes work together, its time zone and dialing, and how to get a 339 number.

Where is the 339 area code?

The 339 area code location is the inner suburbs of Boston, Massachusetts — the same area as 781. It forms a ring around the city of Boston (which uses 617 and 857), reaching from the North Shore down through the western suburbs to the South Shore.

Cities and communities inside the 339 / 781 footprint include:

The Route 128 Technology Corridor

The 339/781 ring is built around Route 128 — "America's Technology Highway" — one of the country's original high-tech corridors, and still a powerhouse:

• Technology — Route 128 helped launch the US computing industry and remains a dense cluster of software and hardware firms.
• Biotech and life sciences — Waltham, Lexington, and the western suburbs host a major biotech and pharmaceutical base feeding off Greater Boston's research ecosystem.
• Higher education — Brandeis, Bentley, and proximity to Boston's universities anchor a highly educated workforce.
• Healthcare and finance — large hospital systems and financial-services employers ring the city.

For tech, biotech, healthcare, and professional firms, a 339 or 781 number signals you are part of this prosperous Greater Boston market.

How 339 overlaid 781

The Boston suburbs have changed codes twice:

• 1997: 781 splits off. The suburbs around Boston were originally part of 617. As the metro grew, 781 was created to serve the suburban ring.
• 2001: the 339 overlay. Only a few years later, 781 was running short of numbers. Rather than split the ring again, regulators added the 339 overlay across the entire 781 area, and ten-digit dialing became mandatory.

Existing 781 numbers were untouched; 339 simply adds a fresh supply for the same suburbs.

How 781 and 339 work together

Because 339 overlays 781, the two codes cover identical ground — neither signals a different town or carrier:

• Your existing 781 number does not change.
• Newer lines may be assigned 339, while established ones keep 781.
• Ten-digit dialing is required on every call, even local ones.
• Calls between 781 and 339 are local, with no long-distance charge between them.

Boston is one of the most code-dense regions in the country — the city and its suburbs share eight area codes, including 617 and the 857 area code in the city core.

339 time zone and dialing

The 339 area code time zone is Eastern Time (ET) — EST (UTC−5) in winter and EDT (UTC−4) in summer, the same clock as Boston and New York. Because 339 shares an overlay with 781, ten-digit dialing is required on every call, including from cell phones. A 339 number works for calls and texts on mobile just like any US number: dial 1 339 XXX XXXX from elsewhere in the US, or +1 339 XXX XXXX internationally and from mobiles.

Putting a 339 number to work for your business

A 339 number puts a Greater Boston address on your caller ID without a local lease. For tech and biotech firms, healthcare groups, and professional services selling into the Boston suburbs, a local code reads as familiar and lifts answer rates over an unknown out-of-state or toll-free line.

You do not need a Waltham office to claim one. A cloud phone provider can assign you a 339 number that rings and texts on your existing devices and routes calls anywhere. With a provider like My Country Mobile, you can pick a 339 line, set up routing, an auto-attendant, and voicemail, and be live in minutes.

Staying safe from spoofed 339 calls

Scammers spoof 339 numbers — faking a Boston-suburb prefix, sometimes matching the first digits of your own number — so a call or text looks local. A 339 on your screen does not prove the contact is really in Massachusetts.

A few habits keep you safe:

• Let unknown 339 or 781 calls go to voicemail, and don't tap links in unexpected texts.
• Never share one-time codes, card numbers, or login details with an inbound caller or texter.
• Be skeptical of "utility shutoff," "package delivery," or "your account is compromised" messages that pressure you to act fast.
• Use carrier spam filtering. The FCC's STIR/SHAKEN call authentication framework is why many phones now label these as "Spam Risk."

Key takeaways

• 339 overlays 781 across Boston's inner suburbs and the Route 128 corridor.
• It was added in 2001, after 781 split from 617 in 1997.
• The region runs on technology, biotech, education, and healthcare, on Eastern Time.
• Existing 781 numbers don't change; new lines may get 339, and ten-digit dialing is required.
• You can get a 339 number from the cloud without a Massachusetts address.

Frequently asked questions