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Before You Call Back

Area code 303

Area code 303 serves Colorado, including Denver, Longmont and Fort Lupton (Mountain time). It has been in service since January 1, 1947 and shares its area with 720 and 983.

Numbers starting with 303 drew 2,529 reports to the FTC from Aug 14, 2026 to Nov 11, 2026 and 2,919 complaints to the FCC since November 2023. The number on your screen can be faked, so a 303 number proves nothing about where a call came from.

Location
ColoradoDenver-Aurora-Centennial, CO Metropolitan Statistical Area
Time zone
Mountain
In service since
January 1, 1947
Overlay
Same area as 720, 983
Local calls
Dial 10 digitsArea code needed, even next door
Exchanges in use
784 of 792held by 27 carriers
Projected to run out
3Q 2070NANPA forecast 2026.2

Complaints about 303 numbers

Reports where the number on the consumer's caller ID (or, for the FCC, the number the caller asked them to call back) starts with 303. These are counts of what people reported; the agencies do not verify them.

FTC reports, Aug 14, 2026 to Nov 11, 2026

2,529

FCC complaints since November 2023

2,919

Different 303 numbers reported

4,704

FCC complaints naming a 303 number, by month

November 2023 to October 2026. Source: FCC Consumer Complaints Data.

Show as a table
MonthComplaints
November 202321
December 20238
January 202416
February 20249
March 20248
April 202410
May 202422
June 202419
July 202424
August 202416
September 202423
October 202425
November 202425
December 202410
January 202517
February 202524
March 202532
April 202554
May 202519
June 202519
July 202529
August 202523
September 202516
October 20251
November 202524
December 202513
January 202621
February 202614
March 2026214
April 2026278
May 2026293
June 2026367
July 2026512
August 2026276
September 2026287
October 2026127

What people said 303 calls were about

Subjects picked in FTC reports, August 14, 2026 to November 11, 2026. 1,519 of 2,529 reports were robocalls.

Show as a table
SubjectReports
Other1,420
Medical and prescriptions295
Dropped call or no message216
Calls pretending to be government, businesses, or family and friends169
Home improvement and cleaning106
Warranties and protection plans89

Most reported 303 numbers

Numbers with at least five reports from three or more places in the last twelve months. Many of them are likely spoofed.

Places served by 303

NANPA lists 13 rate centers for 303. A rate center is the town or district a block of numbers is tied to for billing; sorted here by how many exchanges each holds.
  • Denver735
  • Longmont18
  • Fort Lupton11
  • Deckers5
  • Keenesburg3
  • Allenspark-Lyons2
  • Deer Trail2
  • Georgetown2
  • Hudson2
  • Bennett1
  • Byers1
  • Roggen1
  • Strasburg1

Phone companies holding 303 exchanges

Each exchange (the three digits after the area code) is assigned to one carrier. 29% of these exchanges are pooled: their numbers are handed out in blocks of 1,000 to other carriers, so the holder below is not always the company serving a given number.

Exchanges held, top 8 of 27 carriers

NANPA central office code assignments, file of November 11, 2026.

Show as a table
Carrier (legal name)Exchanges
Qwest Corporation448
Cellco Partnership dba Verizon Wireless - CO60
Level 3 Communications, LLC - CO58
T-Mobile USA, Inc.39
New Cingular Wireless PCS, LLC35
Mcimetro Access Transmission Services LLC31
Spok, Inc.31
Teleport Communications America, LLC - CO28

When today's 303 exchanges were assigned

Exchanges still assigned, by year of assignment. Exchanges returned since are not counted.

Show as a table
YearExchanges
20014
20021
20043
20057
20067
20073
20081
20111
20121
20191
20213
20222
20231
20241
20251

Check a 303 number

A check shows the carrier and rate center of the number's exchange and every FTC and FCC report about that exact number. Why the number on screen can be fake.

Other area codes in Colorado

NANPA area code database and central office code file of November 11, 2026; FCC complaints November 1, 2023 to November 11, 2026; FTC reports August 14, 2026 to November 11, 2026. How the data is used.

Official sources (7)Show