Customer Information

Internet Services

Introducing ADSL
What is ADSL?
What equipment is required to connect ADSL?
How does ADSL work?
The benefits of ADSL
Frequently Asked Questions

Introducing ADSL 

ADSL (Asymmetric Digital Subscriber Line) is a type of Internet connection that allows you to have high-speed Internet access.

What is ADSL? 

Asymmetric digital subscriber line (ADSL) is a broadband technology offering Internet access up to 20 times faster than standard dial-up connection. ADSL is an ‘always on’ service that allows you to be on the Internet anytime your computer is turned on.

ADSL uses a special modem that optimises the phone line so that it can be configured to accept both data and voice calls at the same time, allowing you the freedom to make calls from your phone without having to install a second line.

‘Asymmetric’ means data is transmitted ‘downstream’ to the customer faster than it is sent ‘upstream’ to the service provider. This meets the data needs of most Internet users, that is, users who typically download substantially more data than they upload.

The available speeds for ADSL connection are 256/64, 512/128 and 1500/256 kilobits per second (kbps). For example, 512/128 represents the maximum speed achievable for downloads is 512 kbps, while the maximum speed achievable for uploads is 128 kbps.

What equipment is required to connect ADSL? 

You will require some or all of the following:

ADSL Modem  

  • An ADSL modem differs from a standard dial-up modem and will be required to activate this service.


  • A splitter is used to separate the voice and data traffic into 2 separate lines. The telephone signal is connected to the circuit in the building which is connecting to the phone and the other digital line connects to the customer’s ADSL modem. This can be installed inside or outside the home or office.
  • If a splitter is not used, telephone calls may be affected by interference when the ADSL is connected. The ADSL connection may also be affected by telephone calls.


  • A filter is a small plug that fits between the phone jack on the wall and the telephone. These plugs are used instead of a splitter and need to be fitted to every phone in the home.
  • If a filter is not used, telephone calls may be affected by interference when the ADSL is connected. The ADSL connection may also be affected by telephone calls.


  • Modem drivers are included with the modem and manual settings for the configuration of your computer will be sent with our Welcome Letter.

How does ADSL work? 

ADSL offers high speed data rates for fast file transfers and Internet downloads. ADSL uses the copper telephone lines which currently carry your voice traffic to deliver broadband Internet. An ADSL modem connects the telephone line to your computer. The modem splits communication into 2 channels, one for voice (telephone calls) and the other for digital data (computer communication).

Different frequencies are used for each channel to minimise interference and call quality filters are used to further reduce interference from equipment that share the same telephone line, such as fax machines.

ADSL is dependant on the type of telephone line used and whether your local exchange supports ADSL. The distance to the local exchange may also affect the availability of ADSL service.

An ADSL modem transmits information. The phone line’s bandwidth is divided into 249 different bands, and a virtual modem is assigned to each band. Each of these 249 virtual modems tests its band and operates with the slice of bandwidth it is allocated.

The splitter works by separating the noise coming along the phone line into 2 categories; low frequency noise (voice) and high frequency noise (ADSL). The low frequency noise is channelled through to the phone, and the high frequency noise is channelled through to the ADSL modem.

A filter separates unwanted noise in the ADSL line and is fitted to every phone you want to use in your home. Unlike splitters, these are very easy to install.

Either a splitter or filter must be installed to use ADSL if the line is also used for voice calls, fax or other data products.

The benefits of ADSL 

  • ADSL is accessible 24 hours a day, 7 days a week.
  • Calls can be made from the telephone without disconnecting from the Internet, or installing a second line.
  • Large files can be downloaded quickly.

Frequently Asked Questions 

Here are some frequently asked questions about the ADSL service. If you have any problems, please call our Customer Care number.

How can I make my Internet connection secure?

  • Any connection to the Internet carries some risk. At the very least all personal computers should have an up to date antivirus programme installed. As ADSL provides a dedicated Internet connection over private telephone lines, this reduces the risk of any data being accessed by hackers over a shared network. An ADSL router can offer additional security. For maximum security a firewall as well as other hardware and software solutions should be explored.

Are there any special requirements if the building is equipped with a monitored alarm?

  • If the building is protected by a monitored security alarm, make sure that it was fitted with the correct type of filter, or make sure a splitter is installed. Without these, communication with the security company will cause connection problems with the ADSL modem.
  • We suggest you notify your security company and advise of possible disruption of service.

Is ADSL available to everyone?

  • ADSL is not currently available to everyone. Some factors which may exclude you from ADSL include the distance you live from your exchange and whether you have a dedicated line or split line.
  • If unsuccessful activation is due to a split line, a technician will be sent to resolve the issue. There may be costs associated with this service.

How will I know if ADSL is available to me?

  • We are unable to guarantee availability until we attempt activation and the network provider provides confirmation of a successful connection.
  • If activation is unsuccessful, we will contact you.
  • If activation is successful, we will contact you.

How long will it take for ADSL to be activated?

  • The activation period is approximately 3-5 working days, depending on availability. If you are eligible to participate in the churn (rapid transfer) process your activation time is likely to be a lot less.

Can I use my existing ADSL modem?

  • Yes, you can, however, we may not be able to provide full support should a problem with this modem arise.

Why do I need to install a splitter or filter?

  • If you do not have either a splitter or filter installed, then you may hear interference through the telephone when ADSL is connected. Your ADSL connection may also be affected when you make telephone calls.

Where can I find the minimum system requirements for ADSL?

  • The minimum system requirements for ADSL can be found on our website, or by calling our Customer Care number.

Current as at 28/04/2008