DSL Internet in the USA

Written by Mar 23, 2021

Digital Subscriber Line Internet In the United States


As one of the older internet connections, DSL internet’s nationwide availability keeps it relevant compared to newer connection types, like cable and fiber. Suburban residents and city-dwellers may shy away from DSL due to preconceptions about it having slower speed. But DSL actually can offer enough speed to satisfy the internet usage of most households. Whether you’re in search of a new internet option or just curious about DSL, here’s a primer to help clarify what DSL is, how it works, and who DSL internet is best for.

Are you a journalist or researcher writing about this topic?

Contact us and we'll connect you with a broadband market expert on our team who can provide insights and data to support your work.

What is DSL internet?

Digital Subscriber Line (DSL) is a “last mile” connection that allows consumers to access the internet by using existing telephone lines.

DSL is often confused with dial-up internet since both are delivered via the telephone infrastructure. However, DSL is quite different on a technical level. By using higher frequency bands within a telephone line to deliver data, DSL is able to establish a separate, “always on” channel connection, unlike the low-frequency bands that dial-up phone communications travel by. Effectively, this means it will not cut off landline access when in use, which results in a several times faster connection than dial-up.

How does DSL internet work?

Overall, DSL internet works like tin cans on a string: two sender/receivers connected by a wire.

The “can” on the customer’s side is a DSL modem, translating data into webpages and online applications. The string is a telephone cable, which carries data in the form of an electromagnetic signal. The “can” on the internet provider’s side is a decoding device called a digital subscriber line access multiplexer (abbreviated “DSLAM”), designed to route many connections at once and communicate with the internet “backbone.”

Parts of a DSL network

Real-world applications are a bit more complex — there are multiple pieces that make up a DSL connection and at least four through which data travels.

Parts of DSL Network

  • Copper phone line: Used to send/receive data, copper phone lines are made by twisting two copper wires around one another which decreases interference between the wires and repels electromagnetic interference from outside.
  • DSLAM (digital subscriber line access multiplexer): A device that receives, decodes, and transmits electrical signals to many phone lines at once.
  • Extender: Also called a “loop extender,” DSL extenders are placed between the DSLAM and subscriber modem to boost the signal within the copper cable, allowing the signal to reach rural customers situated far from the local DSL provider office.
  • DSL Filter: A small device that plugs into a phone jack and separates low-frequency phone signal from high-frequency broadband signal.
  • DSL Modem: A device installed in a subscriber’s residence, designed to “translate” the electrical signal from the DSL provider into data for a computer or router.

To visualize how data travels via DSL, we picture the telephone cable as a highway. The “lane” for traditional telephone traffic is only 4 Khz wide — but the width of the highway is about 3000 times wider than that, stretching all the way up to about 12,000 Khz .

DSL Highway

While this is “narrower” than the frequencies possible in a fiber or coaxial broadband connection, it still allows for quite a bit of room to rapidly transmit data.

The anatomy of a telephone cable is very simple compared to other broadband cable technologies. Little has changed since Alexander Graham Bell created the first telephone cable: two copper wires twisted around each other inside a protective coating.

Copper Telephone Cable Anatomy

Telephone wire cross section

Each household’s DSL connection can vary depending on what type of DSL they have.

Types of DSL

There are 14 different types of DSL service. The two most common are ADSL and VDSL.



ADSL stands for “asynchronous digital subscriber line.” The term “asynchronous” is used because much more bandwidth is allocated for downstream data than upstream data. The ADSL specification has evolved over time, with the latest upgrades called ADSL2 and ADSL2+. While ADSL and ADSL2 use the spectrum band from 2.5 Khz to 1.1 Mhz, ADSL2+ uses twice as much, stretching all the way up to 2.2 Mhz. ADSL can theoretically achieve speeds of up to 24 Mbps down and up to 3.3 Mbps up, but real-world applications are usually a fraction of that — around 10-15 Mbps down and up to 1-3 Mbps up.


VDSL, or “very-high-bit-rate digital subscriber line,” uses advanced modulation and transmission hardware to utilize even higher frequency bands, from 25 Khz all the way up to 12 Mhz. This allows VDSL to achieve speeds of 300 Mbps down, 100 Mbps up. However, this capability quickly lowers in real-world settings, depending on the subscriber’s distance from their ISP’s nearest extender or DSLAM.

Should you get DSL internet?

DSL’s main benefit is its availability. However, the list ends there depending on where you live. For instance, city-dwellers are more likely to have faster connections like cable and fiber available. On the other hand, DSL internet is usually the fastest connection available in suburban and rural areas.

The best way to decide if DSL is right for you is to determine what you use your internet for. For example, online activities that require instant reactions, i.e. video calls and first-person shooter (FPS) games, require an internet connection with low latency: a trait DSL internet does not have. If you have cable and fiber also available to you, it’s best to look into how DSL compares to cable and fiber internet before making your final decision.

Pros and Cons of DSL Broadband


  • Widely available via traditional phone infrastructure
  • Affordably priced compared to cable, fiber, and fixed wireless
  • Direct connection from residence to ISP prevents peak-use slowdown


  • Generally provides lower speeds than other broadband technologies
  • Connection quality dependent on distance between residence and ISP
  • Above-ground cabling susceptible to disruption from storms

Largest DSL Providers

  1. EarthLink
    51.07% Coverage
    > 51.07
  2. AT&T Internet
    37.92% Coverage
    > 37.92
  3. Verizon High Speed Internet
    15.14% Coverage
    > 15.14
  4. CenturyLink
    14.94% Coverage
    > 14.94
  5. Frontier Communications
    9.43% Coverage
    > 9.43
  6. Windstream
    4.37% Coverage
    > 4.37
  7. GTT Communications
    1.60% Coverage
    > 1.60

States with the most DSL coverage

  1. Guam
    98.4% Coverage
  2. Vermont
    97.4% Coverage
  3. Connecticut
    95.8% Coverage
  4. Maine
    95.7% Coverage
  5. New Hampshire
    95.3% Coverage
  6. Utah
    94.9% Coverage
  7. Hawaii
    94.5% Coverage

DSL Providers: Availability by State

Alabama 4,253,172 86.6% 52 DSL Providers
Alaska 685,374 91.5% 23 DSL Providers
American Samoa 48,732 89.4% 2 DSL Providers
Arizona 6,171,386 89.9% 42 DSL Providers
Arkansas 2,645,207 87.7% 34 DSL Providers
California 36,144,124 93.5% 71 DSL Providers
Colorado 4,987,221 93.5% 61 DSL Providers
Connecticut 3,479,771 95.8% 26 DSL Providers
Delaware 667,061 70.8% 13 DSL Providers
District of Columbia 584,015 93.6% 21 DSL Providers
Florida 18,651,546 93.8% 48 DSL Providers
Georgia 9,467,383 92.2% 64 DSL Providers
Guam 158,382 98.4% 2 DSL Providers
Hawaii 1,341,752 94.5% 7 DSL Providers
Idaho 1,478,236 88.5% 35 DSL Providers
Illinois 12,175,903 93.7% 93 DSL Providers
Indiana 5,980,387 90.1% 71 DSL Providers
Iowa 2,667,570 86.1% 142 DSL Providers
Kansas 2,516,412 86.1% 49 DSL Providers
Kentucky 3,964,172 88.8% 42 DSL Providers
Louisiana 3,976,089 86.6% 32 DSL Providers
Maine 1,286,015 95.7% 29 DSL Providers
Maryland 4,569,038 76.5% 31 DSL Providers
Massachusetts 5,940,348 89.5% 27 DSL Providers
Michigan 8,962,975 91.1% 73 DSL Providers
Minnesota 4,878,203 89.4% 89 DSL Providers
Mississippi 2,595,315 86.1% 36 DSL Providers
Missouri 5,485,696 89.4% 74 DSL Providers
Montana 936,874 91.4% 29 DSL Providers
Nebraska 1,608,840 85.7% 54 DSL Providers
Nevada 2,624,415 89.3% 38 DSL Providers
New Hampshire 1,277,145 95.3% 22 DSL Providers
New Jersey 7,627,771 85.4% 38 DSL Providers
New Mexico 1,989,569 92.1% 37 DSL Providers
New York 17,821,812 91.1% 63 DSL Providers
North Carolina 9,420,245 93.1% 48 DSL Providers
North Dakota 469,263 67.7% 34 DSL Providers
Northern Mariana Islands 32,087 62.4% 1 DSL Providers
Ohio 10,856,261 93.6% 61 DSL Providers
Oklahoma 3,361,222 86.5% 54 DSL Providers
Oregon 3,523,945 88.2% 68 DSL Providers
Pennsylvania 10,617,973 82.5% 71 DSL Providers
Puerto Rico 1,801,157 49.8% 5 DSL Providers
Rhode Island 848,895 80.8% 15 DSL Providers
South Carolina 4,296,168 88.2% 31 DSL Providers
South Dakota 635,051 75.4% 37 DSL Providers
Tennessee 5,763,535 87.2% 50 DSL Providers
Texas 23,809,735 88.3% 116 DSL Providers
Utah 2,829,893 94.9% 41 DSL Providers
Vermont 614,855 97.4% 17 DSL Providers
Virgin Islands 60,492 58.2% 2 DSL Providers
Virginia 6,667,224 79.6% 51 DSL Providers
Washington 6,459,182 91.3% 55 DSL Providers
West Virginia 1,653,899 88.3% 14 DSL Providers
Wisconsin 5,262,737 90.6% 99 DSL Providers
Wyoming 505,345 85.4% 25 DSL Providers