ADSL Broadband – Frequently Asked Questions
What is ADSL?
ADSL stands for Asymmetric Digital Subscriber Line. This is the broadband service delivered over a standard analogue BT telephone line. ADSL delivers a faster speed downstream (from the Internet to the customer) than upstream (vice versa) and is hence termed “asymmetric”. This is because users typically request four times as much data from the Internet then they send to it.
ADSL broadband is anything from 10 to 20 times faster than ordinary dial-up downstream and around 5 times faster upstream. It is also “always-on” which means that, as long as your PC or network is switched on, it is permanently connected to the Internet. So there's no waiting to dial-up and connect every time you want to collect e-mail or surf the web.
How does it work?
The service splits the signal which travels over your telephone line into two channels. One channel is used for normal voice calls and the other for high speed broadband data. The broadband data uses a frequency range not used for voice communications so the two channels don't interfere with each other.
How do I connect to ADSL Broadband?
ADSL is delivered over your standard BT telephone line to your phone socket. Your ISP will provide you with microfilters which are small adaptors which plug into your phone socket. These separate out the voice and data signals and have one socket for your phone and another for your PC or network. You will need a microfilter for each telephone you are using, including those on wired extensions. The microfilter also allows you to use one socket for both telephone and broadband connection if you so wish.
To connect your PC to broadband you will need an ADSL modem. You can buy these from most PC component suppliers or most ISPs can provide you with a suitable product. ADSL modems connect from the USB or Ethernet port on your PC - virtually all modern PCs have at least one of these.
If you have a network or want to connect several PCs to your broadband connection you will need an ADSL router. These can be bought at varying levels of cost and sophistication and are available for both wired or wireless networks.
Can I make calls at the same time as using the Internet?
Yes, unlike dial-up Internet access, you can make and receive calls even when your line is being used for the Internet. If you currently have a second line just for Internet access you may now be able to do away with this and save money on line rental.
What choice of services are on offer?
This will depend on your ISP. Generally speaking, the ADSL services available can be divided into three categories:‑
· Standard services – speed of 512kbps downstream and 256 kbps upstream. Available at contention ratios of 50:1 and 20:1
· Premium services – speeds of 1Mbps and 2Mbps downstream and 256kbps upstream. Also available at contention ratios of 50:1 and 20:1
· “Lite” services – speeds limited to 150kbps or 250kbps downstream
For the majority of users, the standard service at 50:1 contention will be perfectly sufficient and provide a good broadband experience. This type of service is available for around £29.99 per month (inc VAT) or less.
Heavy Internet users of applications like interactive gaming or business users sharing their broadband connection over a network may benefit from the higher speed premium services. There are a wide range of service packages available. Contact your ISP or seek professional advice if you need more information about these services.
“Lite” services are not true broadband because of the restricted bandwidth available. They should be considered as alternatives to dial-up services and are only sufficient for modest e-mail usage and limited Web surfing.
Most broadband services do not impose any limits on the amount of data downloaded by users (subject to their acceptable use policies). Some schemes recently launched do impose monthly limits on data downloaded in return for a much lower monthly fee than the equivalent standard service. Whilst these limits may seem quite generous to dial-up users, it's worth pointing out that broadband users do make much greater use of the Internet and may well exceed the monthly quota.
For an objective comparison of the services available from the major ISPs, we recommend www.adslguide.org.uk.
What is Contention Ratio?
The Internet is a medium which you share amongst other users and the same applies to your broadband connection. The contention ratio represents the maximum number of users you will be sharing your connection with. In practice you won't all be online downloading at the same time so you won't notice any significant reduction in speed.
The two levels of contention available in the BT ADSL network are 50:1 and 20:1. In theory this means that you could be sharing your connection with up to 50 users but in practice this is unlikely to happen and most users are able to download at the quoted speed.
Do I have to deal with BT?
No! When you order ADSL from ORB we will arrange to BT to test and convert your telephone line to broadband. You can of course choose BT as your Internet Service provider if you wish.
No I still have to pay line rental to BT as well as the cost of ADSL?
Yes. BT's telephone billing (line rental and call charges) are unrelated to your ISP's ADSL service. However you will only have to pay call charges if you make voice calls, you will not be charged any extra for broadband?
Will I have to pay for calls to the Internet?
No. ADSL broadband is “always on” and the price of connection is included in our monthly charge.
How secure is ADSL Broadband?
No system is 100% secure and there is much written about the increased risk that broadband connections to the Internet pose. Since ADSL provides an “always-on” connection to the Internet we strongly recommend that you install a firewall to prevent unauthorised access from the Internet. Customers handling confidential data may wish to consider implementing their own security measures such a Virtual Private Network (VPN).
The major threat to most users from the Internet is viruses which are a danger whatever type of connection you use. As a matter of good practice you should ensure that anti-virus software is installed on your PCs and that this is regularly updated.
Can ADSL be installed on my ISDN line?
No. Unfortunately the ADSL provided over BT telephone lines is incompatible with ISDN (or Home/Business Highway). If you wish to have ADSL installed over an existing ISDN line it will have to be converted back to a standard analogue line by BT. Your ISP can arrange that conversion though it may be subject to an additional charge.
Are there any limitations on the availability of ADSL?
The availability of ADSL is limited by the length and quality of the telephone line from your premises to the local exchange. As a general rule, ADSL cannot currently be installed where the line length exceeds 6km (though BT are testing whether this can be extended to 10km). Higher bandwidth services of 1-2Mbps are typically limited to a 2km line length. Note that telephone cables may not be laid in the most direct route between your premises and the exchange. If the provision of the ADSL service required appears to be marginal then an test on your line will be undertaken by BT.
In addition to ISDN, ADSL broadband cannot be provided on lines used for security alarms and on those fitted with line-sharing devices. Your ISP should check for this when you place your order.
What Operating Systems can be used with ADSL?
This will depend on your ISP but should be the same as those supported for dial-up. In practice this means that any operating system which can connect to the Internet should be supported by ADSL.
Can I connect more than one computer up to the Internet with ADSL?
Yes. If you have 2-3 computers running Windows 2000 or XP and want to share the broadband connection, you can network the PCs together. Connect one PC to your broadband line through an ADSL modem and configure this as the Internet gateway with Internet Connection Sharing switched on. You will then need to configure the other PCs to use this machine for Internet access.
If you have more than 3 PCs or run a business network, we recommend that you use an ADSL router.