FAQ
What is ADSL?
What are the key benefits of ADSL for
me?
What are the key benefits of ADSL based
services for Business?
How fast is it?
Who are our ADSL based services aimed
at?
What can ADSL be used for?
When will I be able to have ADSL installed?
How have BT chosen which exchanges get
ADSL enabled first?
What do I need in order to be ADSL serviceable?
Are there any Service Constraints I
should be aware of?
What services on my line are incompatible
with ADSL?
How does ADSL work?
Is my fax compatible with an ADSL set-up?
Will ADSL affect my normal telephone
connection?
Will telephone calls be charged separately?
Can customers keep an existing telephone
number?
Who is responsible for billing?
Will all BT Select services be supported?
Will ADSL affect my burglar or security
alarm system?
What computer equipment do I need?
Can you tell me more about the line
testing and validation?
What is the minimum contract period?
If I move premises what will happen
to my ADSL connection?
Who do I report faults to?
Is it dangerous to be permanently attached
to the Internet?
Which IP services are compatible with
ADSL?
Can you explain how the contention
ratios work?
Do ADSL services work with non-BT PSTN
lines?
What standard does BT's ADSL modem
adhere to?
Will BT be blocking any TCP port numbers?
What about other technologies?
FAQ Disclaimer
What is ADSL?
ADSL, or Asymmetric Digital Subscriber Line technology is
a means of transmitting digital information at high bandwidth down
existing copper telephone cable. It is permanently 'switched on',
unlike normal dial up access and is asymmetric in that it uses most
of the available bandwidth downstream. This makes it particularly
suitable for applications where customers expect to receive more data
than they transmit such as for Web browsing, use of corporate intranets,
and reception of digital audio-visual material. The technology also
supports analogue connection on the same line, which enables voice
or fax calls to be made simultaneously.
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What are the key benefits of ADSL for
me?
Firstly, the Speed. ADSL provides high-speed digital access
- e.g. potentially 10 to 40 times faster than today's typical modems.
It’s Always On. You will no longer have to waste valuable time
obtaining a dial-up connection to your Internet Service Provider or
Corporate Intranet It’s Flexible. It does not affect the normal
telephone, so you can make and receive telephone calls or faxes whilst
you’re online.
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What are the
key benefits of ADSL based services for Business?
ADSL based services will allow SME's and Corporates to:
* Take full advantage of broadband capabilities.
* Offer innovative services to your end user base.
* Extend the reach of your Intranet to encompass your remote teleworkers
and satellite offices.
* Manage and predict your costs with the flat rate charging scheme
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How fast is it?
Typical rates for ADSL are shown in the table below. Downstream speed
Upstream speed Up to 500 kbit/s Up to 250 kbit/s Up to 1 mbit/s Up
to 250 kbit/s Up to 2 mbit/s Up to 250 kbit/s This is between 10 to
40 times faster than today's typical modems.
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Who are our ADSL based services aimed
at?
Our services are aimed at a wide range of consumers. Corporate business
users will be able to provide their teleworkers or satellite offices
with remote access to the corporate network, whilst home users will
be able to take advantage of the incredible download speeds to view
digital media on the Web, such as movies, music and similar bandwidth
hungry applications.
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What can ADSL be used for?
ADSL's higher potential bandwidth has the potential to enhance access
to existing services and applications and stimulate the development
of new ones: Internet access The
access speeds available with ADSL available make it practical for
web sites to carry more multi-media rich information such as embedded
video clips, animations and good quality audio - significantly enhancing
the online experience Intranet access
Fast access to the Intranet makes teleworking an attractive option
- which in turn can bring benefits to both the organisation and the
individual TV based services ADSL
can be used to deliver interactive applications to the TV, such as
real time video and audio, home shopping and home banking.
Future services
ADSL will be the catalyst for a wealth of new information, education
and entertainment services
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When will I be able to have ADSL installed?
Broadband is dependent upon BT's roll-out schedule for ADSL
serviceability of your geographical area.
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How have BT chosen which exchanges
get ADSL enabled first?
BT have chosen a number of criteria to establish which exchanges should
be provisioned for ADSL first. These included demand for bandwidth
and where the early adopters of these services are most likely to
be located.
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What do I need in order to be ADSL
serviceable?
There are a number of factors that will determine whether you will
be able to take advantage of ADSL. These
include: That you are a BT subscriber. You must have a valid
contract for the use of a BT analogue direct exchange line forming
part of the BT network over which the ADSL service will be provided.
Note that if you rent your premises, you must have a valid contract
for a BT or Calls & Access provided PSTN line. It is not suitable
that the contract be held with your landlord rather than yourself.
Whether BT has upgraded your telephone exchange to ADSL technology,
and whether you are located within a specified distance from the exchange.
That you are aware of the installation procedure and requirements
in terms of equipment as well as location. That there are no incompatible
services on your PSTN line. That you have sufficient mains power sockets
for the BT NTE (Network Terminating Equipment
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Are there any Service Constraints I
should be aware of?
The transmission performance of some local loops will mean
that it is technically impractical to deliver ADSL service to all
end users with a particular serviceable area. BT reserves the right
to refuse ADSL installation even if you are situated in a serviceable
area.
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What services on my line are incompatible
with ADSL?
ADSL service is not compatible with these BT services: Subscriber
private metering 30k loop Private circuits Red ABC RedCare Meterpulse
facility PBX lines It is only possible to provide a single broadband
service over a single BT or Calls & Access PSTN exchange line.
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How does ADSL work?
ADSL operates over a normal telephone line. This means that
there is no need to dig up any roads to replace cable and install
it. The ADSL signal is carried by two ADSL modems - one in the end
user's premises and one in the local exchange. These ADSL modems are
designed to exploit the physical transmission capabilities of the
copper line to the maximum extent. The resultant ‘broadband’
medium is used to achieve much higher data rates than were previously
possible. Two 'splitters' (filters), one in your premises and one
in the BT exchange, separate the telephony signal from the ADSL signal.
This means that telephone calls can be made at the same time that
data is being sent or received (i.e. a customer can surf the Internet
and still make telephone calls concurrently).
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Is my fax compatible with an ADSL set-up?
It is not guaranteed that your existing fax machine will work after
you have installed ADSL. Please check with the fax machine manufacturer/vendor
to check ADSL compatibility.
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Will ADSL affect my normal telephone
connection?
You may notice a slight change to how your telephone sounds after
you have ADSL installed. This is normal for ADSL lines and is not
a fault. Any standard modems operating on your PSTN line (standard
telephone, not the ADSL line) may operate at a reduced speed after
ADSL installation
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Will telephone calls be charged separately?
Yes. Normal telephone rental and call charges will still apply.
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Can customers keep an existing telephone
number?
Existing BT PSTN numbers will be unaffected; most end users will be
able to keep their existing telephone number.
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Who is responsible for billing?
You will make payment arrangements with us for your ADSL service.
If you have any queries about your ADSL account you should contact
us and not BT. The price, billing and payment for your standard BT
telephony service will remain unchanged and BT’s responsibility.
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Will all BT Select services be supported?
Yes, all Select Services can be supported on the PSTN line,
including Call Waiting, Call Return and Caller Display.
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Will ADSL affect my burglar alarm or
security system?
Installation of ADSL may adversely affect security or burglar
alarm systems that use your PSTN telephone line and fail to operate
correctly. You should check with your suppliers for compatibility
of your system before arranging for ADSL installation.
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Which IP services are compatible with
ADSL?
The service supports most protocols including Telnet, SMTP,
HTTP, FTP, TFTP, VDO, RealAudio, Cu-SeeMe, QUAKE (2.8.0). ADSL will
also support instant messaging and communication programs such as
NetMeeting, ICQ or Microsoft Messenger. Some of the advanced functions
of these programs, such as video conferencing or file sharing, will
not operate behind a firewall or Network Address Translation (NAT)
without some technical configuration, or possibly not at all. If you
have any questions, consult the user Help for the specific program.
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What computer
equipment do I need?
The equipment required and minimum specification of PC depends upon
which installation you are having, USB or Ethernet version. For the
ADSL Home and ADSL NetStart USB installation, you will need the following:
PC with the minimum specification of:
Windows 98 or Windows 2000 operating system USB port (if you are not
sure about this, please see your supplier. The ADSL modem uses USB
to connect to your PC). 4-speed CD ROM drive 200Mhz Pentium or above
32 Mb RAM or higher Video card/display capable of 800x600, 256 colours
SVGA monitor 16 bit sound card 150 MB free hard drive space For the
Ethernet multi-user modem/router installation, you will need the following:
PC with the minimum specification of:
Network Interface Card (10BaseT Ethernet port) TCP/IP communications
stack Netscape 4 or IE 4 or above must be loaded onto at least one
of the PCs connected to the service. The browser must be JavaScript
enabled. Other specifications will depend upon the applications you
want to use with your ADSL service and the operating system you are
using. For basic Internet browsing this should be at least: Pentium
166Mhz, MMX or above 32Mb RAM or above 150MB available hard disk space
SVGA or higher rated monitor Video card/display capable of 800x600,
256 colours Windows 3.11, Win 95 or Win 98 - or, Windows NT or Windows
2000 4-speed CD ROM player 16 bit sound card Mouse or other pointing
device If you wish to use Apple MacIntosh on your network, the machine
should conform to the following specification:
Or a Apple Macintosh with the following is recommended: PowerPC
601 or equivalent 32MB System Memory 2-speed CD ROM player Video driver
and display capable of 800 x 600, 256 colours 100MB free space on
hard drive OS8.1 or higher Open Transport 1.3 Networking Software
10baseT Network Adapter with an RJ45 connector You will also need
appropriate lengths of Ethernet cable to connect your PCs to the ADSL
router/hub. Note that a length of 100 meters must not be exceeded
between the PC and hub.
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Can you tell me more about the line
testing and validation?
After initial ordering, BT engineers will make preliminary
tests on your line to make sure that you are ADSL serviceable. If
the tests conducted on your line show that BT are unable to install
ADSL at your location, you will be told the reason for this. Some
examples of situations may be line quality, distance from the exchange,
incorrect information being supplied upon application etc.
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What is the minimum contract period?
There is a 3 month minimum contract period. You should however contact
us rather than BT if you have any queries.
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If I move
premises what will happen to my ADSL connection ?
Your contract with BT and ourselves is for your specific location
and subject to a minimum period. This minimum subscription period
would remain payable if you move location whether or not your new
location is ADSL serviceable. If you require ADSL at the new premises
then you should make arrangements for a new installation and your
old contract will be replaced by a new one
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Who do I report faults to?
You should report faults to us and not BT in the first instance.
The only exception to this is if the fault affects only telephony
services.
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Is it dangerous
to be permanently attached to the Internet
? Any computer that is connected using ADSL to the Internet
is exposed to the same security risks as a dial-up user, however since
ADSL users are typically connected to the network for longer periods
of time (always on) this risk is potentially that much greater. You
should be aware of the potential of hacking attacks and the precautions
that you should take. Please read our security section. Some
examples of good security practice are: Turn off your PCs when
not in use. Turn off Windows File and Printer Sharing Install a virus
checking software product and ensure that it is maintained to the
latest version. You should provide a Firewall in the case of a sensitive
installation. You should provide encryption of data transmission for
sensitive data.
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Can you explain
how the contention ratios work?
The USB modem and the Ethernet router solutions have different contention
ratios set up by BT, with these values set at 50:1 and 20:1 respectively.
This means that for a Home user with a USB modem, the BT connection
at the exchange is shared with another 50 users. Whilst some degree
of performance loss will be experienced during peak periods, it is
generally accepted that few people will be downloading or uploading
data all at the exact same time. For the business user it makes sense
to go for the 20:1 business version, which will not be subject to
so much slowdown at peak periods. The two systems will be able to
co-exist on the same 'local loop' due to BT's network tunnelling protocols,
each connection being given its own port on the exchange terminating
equipment (DSLAM.
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Do ADSL services
work with non-BT PSTN lines?
Currently the Broadband services are only available over a
BT PSTN line. A non-BT PSTN variant is being investigated.
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What standard does BT's ADSL modem
adhere to?
Various forms of ADSL signal modulation are possible but the
two more prevalent are: Discrete Multi-Tone (DMT), and Carrierless
Amplitude modulation Phase modulation (CAP). DMT uses interleaving
to achieve good error performance and has become the international
standard. BT evaluated both DMT and CAP modems during their extensive
trials throughout 1998 and 1999. However, their commercial ADSL based
services will use DMT. Alcatel and Fujitsu will supply these modems.
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Will BT be
blocking any TCP port numbers? There has been some speculation
in the press regarding the supposed prospect of port blocking on the
ADSL service. The huge popularity of distributed networking programs
such as Napster, Gnutella and iMesh has led to fears of excessive
bandwidth consumption. BT have stated that they have no current plans
to restrict bandwidth use or block particular ports, although they
may review this in the future if the service is adversely affected
by flagrant bandwidth abuse.
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What about
other technologies? What impact will UMTS have on ADSL? Universal
Mobile Telecoms Service - UMTS is the called the 3rd generation mobile
service. It is a mobile network whereas ADSL runs over a fixed network.
So, whilst UMTS will deliver broadband access too, the two technologies
are more likely to be complementary rather than head-on competitors.
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What is DSL Lite technology compared
to ADSL?
DSL Lite/G.Lite is a lower speed, splitterless version of ADSL. It
is designed to offer around 1Mbps of capacity downstream, and 120kbps
upstream. Because there is no Splitter, it is easier to install but
does mean that the end user may experience significant interference
between the telephony and ADSL services when they are used at the
same time. BT's ADSL based services are based on the full ADSL standard,
rather than DSL Lite. BT is involved in the evolution of the standard
for DSL Lite but has no immediate plans to launch services based on
it .
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Disclaimer
Please note that although we endeavour to make sure that the information
included in this FAQ is up-to-date and accurate we cannot guarantee
that it is exhaustive, nor that changes won’t be made at any
time without prior notice.