Introduction
A Denver number that starts with 983 looks unfamiliar to plenty of Front Range residents, and that unfamiliarity has a cost. Print the wrong digit count on a business card, or misjudge which calls need the area code, and a customer's call fails or lands on the wrong line. Colorado's phone system has layered three area codes onto one Denver footprint since the late 1990s, and 983 is the newest. Getting the mechanics right matters more than the number itself.
The 983 area code is a telephone overlay code assigned to the Denver metropolitan area in Colorado under the North American Numbering Plan. It shares the same geographic footprint as area codes 303 and 720 rather than covering new territory, and it exists purely to keep new phone numbers available as the region keeps growing. Regulators activated it in 2022 once demand in the existing overlay outpaced supply. What follows covers where it reaches, how it compares to its neighbors, and how a business anywhere gets one.
What Is the 983 Area Code?
Every area code in the U.S. and Canada belongs to the North American Numbering Plan, which keeps ten-digit numbers from colliding across states and provinces. When a region runs low on numbers, regulators add capacity one of two ways: a geographic split that draws a new line on the map, or an overlay layering a second code over the same footprint.
Area code 983 went into service on June 17, 2022, the fifth area code assigned in Colorado and third to serve Denver. Colorado's Public Utilities Commission chose the overlay route, the same approach it used for 720 twenty-four years earlier.
It sits alongside 303 and 720 rather than replacing either; existing numbers stay exactly as issued. Only new lines requested after that date draw from the 983 range.
Where Is the 983 Area Code Located?
The 983 area code marks no new territory. It reaches exactly as far as 303 and 720, covering Denver's urban core and a wide ring of suburban Front Range communities.
Cities and Communities Covered
Businesses and residents across the metro can be assigned a 983 number, including Denver, Aurora, Boulder, Lakewood, Thornton, Westminster, Arvada, Centennial, Longmont, Littleton, Wheat Ridge, Broomfield, Highlands Ranch, Castle Rock, Commerce City, Brighton, Englewood, Erie, Golden, Northglenn, Fort Lupton, and Strasburg.
That range runs from the Boulder foothills to Castle Rock, covering most of the metro corridor along Interstate 25. Any of those communities can receive newly issued 983 numbers from carriers serving the area.
Counties Included in the Overlay
The overlay spans Denver, Arapahoe, Jefferson, Adams, Boulder, Douglas, and Broomfield counties. A 983 number can land in any of them, since assignment depends on the carrier and central office handling the request, not which side of a county line the customer sits on.
Is 983 New, or an Overlay of an Existing Code?
Colorado ran on a single area code, 303, for its first forty years starting in 1947. When the region grew, regulators chose overlays over map splits. Denver gained 720 as its first overlay in 1998, setting the template for everything since.
Growth forced geographic splits first: the south became 719 in 1988; the north and west became 970 in 1995. But for Denver's densest metro zone, regulators chose the overlay approach. Twenty-four years later, the same footprint filled up again, and 983 arrived as a second layer.
That decision set the template for the whole state. The pattern continued in 2025, when 970's territory got its own overlay, code 748—and in St. Louis, the 557 area code followed the same logic, arriving in August 2022 after a two-decade delay. Overlays, not splits, are now how regulators handle growth in an established footprint.
983 vs. 303 and 720: What Actually Changes
Nothing about a call's price, path, or classification changes because it touches a 983 number. Colorado's regulators were explicit on this point: a call that was local before stays local, and existing 303 or 720 customers keep their numbers with no forced reassignment. Same wires. New label.
What changes is narrower than expected: only newly requested lines and additional numbers for existing customers draw from 983, because the 303 and 720 pools are nearly exhausted. A side-by-side view makes it concrete:
| Detail | 303 | 720 | 983 |
|---|---|---|---|
| Status | Original code, 1947 | First overlay, 1998 | Second overlay, 2022 |
| New numbers issued? | Rarely (ported only) | Yes | Yes |
| Geographic coverage | Denver-metro | Same as 303 | Same as 303 and 720 |
| Local call rates | Unchanged | Unchanged | Unchanged |
| Dialing requirement | 10-digit | 10-digit | 10-digit |
The dialing row is the one detail that surprises customers coming from markets where 7-digit dialing is still normal. In Denver, the 10-digit rule has been in force since 1998, so every device, system, and contact list in the metro already dials the full number. A new 983 line simply fits into a calling culture that has had over two decades to adjust.
Do You Need to Dial 10 Digits for 983 Numbers?
Every call within the 303/720/983 complex requires all ten digits: area code plus the seven-digit number. Dial only seven digits and the call won't connect. This has been the rule for the entire metro area since long before 983 existed.
It's a common assumption that 983 made ten-digit dialing mandatory in Denver. Not accurate: the rule dates to June 1, 1998, when 720 was activated, twenty-four years before a 983 number existed.
The FCC's dialing guidelines mandate full number dialing across all overlay regions to prevent digit conflicts. Anyone dialing ten digits out of habit has already been living with a rule 983 simply continues.
What Time Zone Does 983 Use?
Every 983 number operates on Mountain Time: UTC-7 for Mountain Standard Time, UTC-6 for Mountain Daylight Time, with the shift following the national schedule, forward the second Sunday in March, back the first Sunday in November.
For a business outside Colorado, that gap against the East Coast, or the wider one against Europe, is worth building into staffing schedules. A support line answered from Lagos or London needs to know a Denver 9 a.m. is already mid-morning back home.
How to Get a 983 Area Code Number
No Colorado address, business license, or local presence is required. Any individual or business can provision a 983 number through a wholesale VoIP or cloud provider, most of it online in one sitting.
Businesses that already hold a Colorado number can port it to a new provider instead of starting over, and most carriers handle the transfer without downtime. The same path works from anywhere with an internet connection, which is why 983 suits teams that want a Denver presence without relocating staff.
Will a New 983 Number Get Flagged as Spam?
Newly opened area codes carry a quiet disadvantage: spam-detection systems have less history to work with, and robocall operators have historically rotated through fresh blocks to dodge blocklists. That blank slate means a legitimate business calling from a new 983 number can get caught by the same suspicion aimed at spoofed traffic, especially soon after issuance.
STIR/SHAKEN is the industry framework built to push back on that problem. Carriers cryptographically sign outbound calls to certify the caller ID matches the real number, and calls with full attestation rarely show a "Scam Likely" warning. A provider that signs every call at the carrier level gives a new 983 number a better shot at getting answered. It works.
Why Businesses Choose a Local 983 Number
A local area code signals something a toll-free number doesn't: familiarity. Front Range customers answer a recognizable 983, 303, or 720 prefix more readily than an unfamiliar one, and that trust advantage compounds across hundreds of outbound calls a month.
The more interesting shift is who's requesting these numbers. A growing share of 983 activations go to teams with no desk in Denver: a support queue in another time zone, a remote sales rep, or an international company testing the U.S. market before committing to a lease.
None of that requires a Colorado address or a local hire, just a cloud phone system that routes calls wherever the team sits.
Conclusion
983 is not a new place on the map, a new rate, or a new dialing rule invented just for it. It's a second layer of numbers over the same 303/720 footprint that has served Denver for decades, activated in 2022 because the metro area kept growing and the number pool didn't. Dialing, time zone, coverage, and pricing all carry over unchanged. The only real difference is the three digits on newly issued lines.
For a business weighing a 983 number, the practical questions are simpler than the history suggests: does a Denver presence help you reach customers, and can your phone system hand out that number without an office lease. TKOS has spent more than a decade building carrier-grade voice infrastructure around that same remote-provisioning logic. A Denver number is a routing detail, not a location requirement. Get the mechanics right, and the area code stops being the hard part.
