FAQs What is DSL?
Pro Tips

What is DSL?

Last Updated:

DSL service has come a long way over the past 25 years. When Internet access first became available to the general public in the late 1980s, dial-up Internet was the only option for getting online.

By the late '90s, however, DSL service had moved onto the scene, providing a higher speed connection and improving rural internet options in particular. According to the United States Census Bureau, roughly one in five connected households uses DSL internet service.

Compare Internet, TV, & Home Phone

Compare Internet Providers by ZIP Code

If you're trying to decide whether to choose DSL internet for your home, you'll want to know exactly what you're getting with this technology, and whether it will meet your needs. Following, I've provided an overview of DSL, including what it is, its benefits and drawbacks, and how it's shaping up for the future.

What is DSL?

Originally dubbed Digital Subscriber Loop, DSL is more commonly known today as Digital Subscriber Line. Line and loop both refer to the connection between the phone exchange and your home. The word "line" was adopted as a more consumer-friendly way of describing this connection.

PC Magazine defines Digital Subscriber Line as: "A technology that increases the digital capacity of ordinary analog signal or digital telephone lines (the local loops) into the home or office for the internet and TV service. Depending on the DSL version, speed is based on the distance between the customer and telco central office or telephone junction box."

Essentially DSL is a way of using extra upstream and downstream bandwidth in your telephone company lines to send data signals to your computer or router. This allows home internet service DSL providers to offer access using existing wiring as opposed to having to install all new infrastructure.

What is DSL?

How Does DSL Internet Work?

DSL is a communications technology which allows DSL internet service providers to utilize extra bandwidth available throughout telephone company wiring (typically made of copper wire). Because data signals travel at a higher frequency than voice signals, it is possible to send both via the same route.

Tech education site MakeUseOf uses an effective analogy to explain how this process works. Imagine the voice signals (as when you're talking on the phone) as green marbles being sent down the wiring every 60 seconds.

The data is red marbles, sent every five seconds. You then have the capability to send the data "around" the voice signal, simultaneously, in a way that doesn't interfere with its function. This also means you can talk on the phone at the same time as you're surfing the net because the signals are using different frequencies.

DSL internet works by sending a digital data request instead of an analog signal along the following route:

  • Computer to phone line
  • Phone line to your outdoor phone box
  • Phone box to street wiring
  • Street wiring to phone company exchange office
  • Exchange to your ISP
  • ISP to the internet

As the signal returns to your home, it passes through a filter which separates the telephone lines signal from the internet connection signal. This is so that you don't get audible interference from the data transfer when you talk on your phone.

What is a DSL Splitter?

A DSL splitter is meant to help with phone calls while someone is using the Internet. Traditionally, you weren't able to stay connected to both the Internet and a phone call at the same time because they used the same line.

A DSL splitter fixes the problem and allows you to do both by removing the analog signal from your phone call from your line before it can disrupt your connection.

DSL vs. T1 Lines

If you've ever heard of T1 lines, you may be wondering what in the world they are. A T1 line offers less than DSL when it comes to maximum speed potential. On the other hand, T1 lines are not shared like DSL lines are.

The fact that DSL lines are shared means the Internet can slow down during hours when many people are using it at once. A T1 line fixes this problem.

Types of DSL

There are two commonly used versions of consumer DSL internet service - ADSL and VDSL. There are other variations, however, the DSL internet plans you will be choosing from are likely to be powered by one of these two technologies.

  • Asymmetric DSL: Asymmetric DSL refers to the slower type of DSL connection. Asymmetric means that the download speed - the speed at which information reaches your computer - is faster than the upload speed (the rate at which you can, for example, upload photos to the web). The maximum speed Asymmetric DSL can provide is technically 24Mbps (megabits per second), although in the real world your connection will not typically reach this speed. With this type of connection, DSL Internet service providers offer service which runs anywhere between under 1Mbps to 10Mbps downstream bandwidth and about 1 Mbps or less upstream.
  • VDSL: A Very-high-bit-rate Digital Subscriber Line provides faster speeds, usually at a higher price. These faster speeds are possible because many high-speed internet service DSL providers are installing fiber optic cables from the central office to neighborhoods. This means that even if the wiring running from the street to your home is still copper wire, you benefit from the higher data transmission rate afforded by the fiber up to that point.
  • DSL Lite - DSL Lite may be cheaper than regular DSL and is faster than dial-up. Some companies, such as AT&T, offer DSL Lite as the first, slowest option in a list of speeds. AT&T has DSL Lite, DSL Ultra, and DSL Extreme, for instance. Prices vary based on your speed of choice.

Related: What Is High-Speed Internet?

The maximum speeds allowed by VDSL can go as high as 100Mbps both downstream bandwidth and upstream bandwidth. This is not the norm in consumer DSL internet service, however.

You're more likely to encounter plans like FastAccess DSL Xtreme from AT&T Internet, which gives you up to 6Mbps downstream speed and 1Mbps upstream speed. DSL is somewhat faster with Verizon Internet - their upper tier plan goes as high as 15Mbps for downloads and 1Mbps for uploads. CenturyLink Internet, however, offers one of the fastest DSL plans, with a plan that claims up to 40Mbps downstream speed and 5Mbps upstream speed.

DSL vs. Cable Internet Access

In a way, comparing DSL internet with cable Internet access is like comparing apples and oranges. Both have distinct advantages and disadvantages, depending largely upon your geographical location.

For instance, if you live in a rural area, you'll likely only have access to satellite internet, dial-up Internet, and DSL. If you do find yourself choosing between DSL and cable internet, you'll want to take the following factors into consideration.

Because cable is a shared connection, you can experience slowdowns during peak usage times if there are a lot of people in your neighborhood online simultaneously.

1. Speed

Cable is capable of higher download speeds than DSL, with some plans delivering up to 100Mbps. However, upload speeds aren't much better on cable than they are on comparably priced DSL plans. For example, the bottom two-tier plans from Time Warner Cable Internet provide upstream speeds of 1Mbps and 2Mbps respectively, similar to DSL upload speeds.

One thing to remember about speed, whether you have a cable or DSL internet connection, is that various factors can affect whether or not you're getting the maximum rate available from your provider. Outdated DSL modems or Cable modems can slow down your upload and download speeds, as can routers which aren't capable of facilitating the latest speeds.

Before assuming it's your provider's fault that your upload and download experience is slower than it should be, address these issues to see if they improve the situation. In the case of DSL, degradation of your home phone wiring may also affect the quality of your connection.

2. Security

Traditionally, DSL internet service has been thought of as more secure, due to the fact that your phone line is your own, whereas cable is a shared line with neighbors.

Cable security has improved, however, with cable companies now pushing security updates through your DSL modem or Cable modem even if you purchased it yourself. Both options are viewed by experts as secure enough for home users.

ProTip: You can improve your internet security a VPN service provider.

3. Reliability of Connection

Despite the lure of potential maximum speeds, both cable and DSL high-speed internet connections can suffer the effects of outside influences.

Because cable is a shared connection, you can experience slowdowns during peak usage times if there are a lot of people in your neighborhood online simultaneously. Even the best cable provider does not have much control over traffic load and patterns and their effect on your online experience.

DSL, even though it's a dedicated line to your home, suffers from a problem called line attenuation. This is the effect of distance on your internet speed. In other words, the farther your home is located from the phone company central office, the slower your connection will be.

Don't assume, however, that just because your home is geographically close to the office that your connection will be faster - the wiring sometimes takes a complex route throughout neighborhoods before reaching your residence. Most providers can tell you the approximate speeds you should expect based upon your location.

4. Cost

My analysis showed that prices between cable and DSL internet and telephone companies are fairly comparable, although there are - as usual - other factors involved. The main price benefit of cable comes with the ability to order cable and internet bundles, such as these bundles here. If you're a cable television subscriber, then you may be able to save a considerable amount on your internet just by bundling the two services together.

On the other hand, because DSL usually requires the use of landline telephone companies, you can bundle your services together for a better rate from DSL internet providers. Several providers, including EarthLink and CenturyLink, now offer a freestanding option, meaning your phone line doesn't have to be active to obtain DSL internet service.

Depending on whether you bundle your services and what speed you want, either cable or DSL internet service may cost you anywhere between $20 and $60 per month. Keep your eye out for promotions, however, because they can mean big savings, at least temporarily.

For example, at the time of this writing, CenturyLink is offering download speeds up to 40Mbps for $35/month for one year. With any provider, whether cable or DSL, you will have to call to see what's available in your area as pricing may vary by location.

Ultimately, unless you need an ultra-fast connection to power multiple enabled devices all running high-demand applications simultaneously, modern DSL speeds are likely sufficient for your household.

Compare Internet, TV, & Home Phone

Compare Internet Providers by ZIP Code

Related: How to Find Internet Plans in Your Area

The Future of DSL Internet

Up until just a couple of years ago, DSL internet was seen as dial-up's quickly aging little brother - the one who's suddenly not that cute anymore, thus not as fun to have around. All that has changed thanks to Israeli tech firm Sckipio Technologies.

What Sckipio did was take a DSL chipset called G.fast and turn it into a 750Mbps powerhouse of data transfer. That's 750Mbps both ways - upstream and downstream.

G.fast is changing the face of broadband internet, giving it the potential to become the best DSL ever available to consumers.

The beauty of this DSL breakthrough is that the G.fast infrastructure is more affordable than fiber optic internet yet just as fast. This means that high-speed internet providers can take the existing phone lines and adapt them to allow a G.fast connection. In fact, these companies are looking at doing that very thing on a large scale as we speak.

You might be asking yourself, who in the world needs 1.5Gbps of data transfer power? The fact is that technologies are evolving on a daily basis. Advances in our online activities require more bandwidth than ever before. For instance, the following are existing technologies which require extremely fast home internet speeds - and they are quickly becoming everyday functions:

  • Virtual reality
  • 4k videos
  • Interactive video games with high-demand graphics
  • Cloud storage for photos and videos

You probably don't need 1.5Mbps of power now, but you likely soon will. G.fast is one of the most promising methods of delivering these speeds to large segments of the country in a time-effective manner.

Another amazing thing about G.fast is that it only loses up to 10% of its speed over distance, as opposed to regular DSL internet service which can lose up to 90% depending upon how far you are from the phone exchange. G.fast is changing the face of broadband internet, giving it the potential to become the best DSL ever available to consumers. Check out our guide on how to get cheap Internet service if you're looking for a more simple alternative.

Recap

Not too long ago, many thought DSL's days were numbered. In fact, in 2011 the CEO of AT&T called the technology "obsolete". This is particularly ironic in retrospect considering that AT&T is now one of the first in line testing out G.fast access in the consumer marketplace. The vast majority of the best internet providers may very well eventually be offering G.fast service.

There's no doubt this type of connection is still the main player in the realm of high-speed internet access. It offers you a convenient way to use your home's existing wiring to get online with a much faster connection than through dial-up, at an affordable cost. Its future is certainly looking bright to boot. If you're looking for the fastest internet providers in your area, use our handy zip code checker to find out which companies serve your location.

Compare Internet, TV, & Home Phone

Compare Internet Providers by ZIP Code