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DSL, ADSL, and ADSL2: What is ADSL and How Does it Work?

ADSL connection with wifi router

Internet speeds are getting faster and more reliable as technology improves, which is great news for the millions of Australians who have had to deal with slow broadband speeds for years. By now, almost everyone has heard of the National Broadband Network or NBN, which has been rolling out and replacing ADSL connections for the last decade. But what exactly was ADSL and why is the NBN better? To find out more about ADSL technology, keep reading below.


What are DSL, ADSL, and ADSL2?

DSL, ADSL, and ADSL2 are older broadband technologies used in Australia, which utilized the copper telephone wires to deliver the internet to homes across the country. Since the rollout of the National Broadband Network began in 2007, traditional DSL broadband has slowly become obsolete.

DSL (also known as Digital Subscriber Line) is the generic term used to categorize services delivered over copper wire (such as broadband). ADSL is a type of DSL known as Asymmetric Digital Subscriber Line, which simply means that service speed (download and upload speeds) will not be the same in both directions as the assumption is most people are downloading more content than they upload. ADSL was once the popular choice in home internet connections, with the faster ADSL2 replacing it for better and more consistent download speeds.

The NBN and copper wires The National Broadband Network still utilizes some of the copper telephone wires for certain types of connections. However, as the NBN has now been rolled out across the country, older connection types that use copper wire are being replaced with fibre-optic cables for even more reliable broadband connection and speeds, known as Fibre-to-the-Premise (FTTP). If you have an FTTP connection, you can potentially reach download speeds of 250Mbps or more.

How does ADSL work?

ADSL is what we call the type of broadband connection that works through the existing copper wires of your phone line, connecting from your home to what is known as an Exchange. Almost every home had, and most still have, a landline connection which made ADSL a relatively straightforward way to connect homes and businesses to the internet.

Many of us remember the old days of dial-up, when we had to make sure no one was using the phone before going online. ADSL solved this problem by using a DSL filter, also known as a splitter, to isolate frequencies and allow one telephone line to be used for both broadband and home phone services without interference.

ADSL speeds - How fast is ADSL?

ADSL when compared to dial-up was, at one point, light years ahead in terms of download speed. However that has since changed, and with ADSL replaced first by a faster ADSL2+, and now an even faster NBN, ADSL speeds are less than impressive by 2021 standards.

Compare ADSL speeds
Broadband connection type Max download speed
Dial 63kbps
ADSL 8Mbps
ADSL2 24Mbps
NBN 12Mbps to 250+Mbps
(Max download speeds vary depending on NBN speed tier)

When looking at ADSL speeds, it’s important to remember the most important factor - distance. How far away your connection is from the exchange will directly affect how fast or slow your ADSL is. As the broadband signal travels from the exchange to your modem, it suffers attenuation (loss), therefore reducing your broadband speed.

Graph displaying ADSL and ADSL2+ speeds decreasing as distance from the exchange increases

What replaced ADSL? NBN vs ADSL

The National Broadband Network, or NBN, is Australia’s effort to expand and improve the broadband infrastructure of the country. Since it was first announced in 2009, the NBN has been replacing the traditional ADSL infrastructure and copper telephone wires with high-speed fibre-optic cables.

The biggest difference between ADSL and NBN is your download speeds, and more specifically the range of speed tiers you can choose from. Traditional ADSL only has a maximum download speed of 8Mbps, while faster ADSL2+ has max download speeds up to 24Mbps. The NBN, on the other hand, has speed tiers starting at 12Mbps.

Differences between NBN speeds
NBN speed tiers NBN speed description
NBN12
Basic
1-2 low-internet users, light web browsing, and emails
NBN25
Standard or Basic II
1-3 average internet users, stream standard quality videos, and browse the internet
NBN50
Standard Plus
2-4 users, online gaming, video streaming, high internet usage
NBN100
Premium
Large households, HD online gaming, multiple devices, high quality video streaming
NBN250 & NBN1000
Superfast & Ultrafast
The fastest NBN plans available. Only for Fibre-to-the-building connections

With the ever-expanding use of the internet, and more powerful technology that comes with it, these faster broadband speeds are becoming increasingly necessary to work from home, game online, stream better quality videos, and keep in touch with friends and family far away.

How do I switch from ADSL to NBN?

Switching to the NBN from ADSL isn’t automatic. Once NBN is available in your area you have 18 months from the date of connection to switch over. After 18 months, your ADSL broadband and phone line will be disconnected.

It’s easy to switch to an NBN plan, however. Most NBN retailers offer flexible plan options, so you can make sure you’re getting the best broadband option for your household. Some things to consider when switching from ADSL to NBN are:

 Speed: As stated, NBN plans are divided into different speed tiers and faster speed tiers coming with a higher monthly cost. It doesn’t make sense to pay for a broadband speed that is unnecessarily fast, while likewise you don’t want to suffer slow internet speeds because of a plan that was too slow.

 Data: Most NBN plans come with unlimited data, but if you’re someone who doesn’t use the internet often it might make sense to consider a capped data NBN plan. It should be noted, however, that these days there really isn’t a price difference between capped and uncapped data plans.

 Contract type: Do you want a month-to-month contract, or a 12-month contract. While month-to-month contracts give you the flexibility to switch providers, they often come with more upfront costs such as activation fees or the cost of a modem. 12-month NBN plans often offer $0 activation, and free modems, in exchange for staying with them for a year.

Do I need to switch to the NBN?

Technically, yes and no. While switching to the NBN is not compulsory, you can’t stay on ADSL forever. This is because of what is known as your NBN cut-off date. All homes in Australia are getting connected to the NBN, and once your area is connected you will have 18 months from the date of connection to switch to your chosen NBN plan. After those 18 months are up, your traditional home phone and internet services will be disconnected.

However, you don’t technically need to connect to the NBN. It isn’t mandatory - there just aren’t many other alternatives to choose from. If you’re dead set against the NBN, home wireless broadband allows you to connect the devices in your home to the internet using the 4G (and, more recently 5G) mobile network.

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