ADSL Primer
What is ADSL?
ADSL (Asymmetrical Digital Subscriber Line) works by splitting your existing telephone line signal into two seperate signals - voice and data.
The average download speed in the UK is around 1MB/2MB although speeds of up to 8MB are possible in certain areas. However, upload speeds are usually around 256Kbps on most services and will never be the same speed as download, hence being called "Asymmetrical".
The vast majority of ADSL services from various ISP's who are reselling the service from network operators, the predominant operator being BT. It is the network operator's sole responsibility to ensure that the service is being delivered to and from your ISP.
Getting Connected
BT Telephone Line
You will need to be within 3.5-5.5 kilometers of an ADSL enabled exchange. BT Wholesale will carry out various tests on your line before the installation begins.
ADSL Modem / Router
Your ISP will normally supply you with a free modem or router as part of their welcome package. There are a number of suppliers selling this hardware, which can be simplified by seperating them into three categories:
- PCI ADSL Modem
This is the cheapest method of getting online with prices falling around the £40 mark. PCI Modems deliver excellent response times although consume CPU cycles to run efficiently.
- USB ADSL Modem
The simpliest method of getting online and the most popular for home users. Slightly more expensive than PCI modems, these retail from around £60, although your ISP may supply you with one free of charge.
- Ethernet/Wireless Router
Most routers act as a gateway, DNS, DHCP and firewall service, making it a robust method of connecting to the Internet. You can also use a router to connect multiple computers to the Internet, eliminating the need for Internet Connection Sharing software.
Micro Filters
A micro-filter is designed to plug into your phone socket (similar to a standard splitter) so that it can seperate voice from data. Every socket in use must use a micro-filter.
However, if you do not own a telephone, a microfilter is not necessary and you will simply need a cable that will fit between your phone line and your modem/router. See Cables.
Cables
RJ-11 Broadband/Telephone Plug
The US style RJ-11 plug is a 4 pin version of the RJ-45. It is the smallest in size and is used in the UK for DSL/Broadband Internet connections (RJ-11 to RJ-11).
BT Plug
The familiar British telephone plug used in over 30 countries around the world. Any analogue device that operates over a telephone line will be connected using this plug. You'll often find an RJ-11 plug on one end, and a BT plug on the other (RJ-11 to BT).
USB Type A (Computer)
USB is the most popular way of connecting peripherals to your computer. To connect most devices, you'll require a type A to B cable (often supplied with the product).
USB Type B (Peripherals)
The other end of the USB wire features a square shape plug designed to connect to peripherals such as your USB DSL modem or router.
RJ-45 Ethernet Network
The RJ-45 connector, featuring 8 pins, is the big brother of the RJ-11. It's used specifically for Local Area Networks.
Cables can be either straight (for normal use between a hub and a computer) or crossed (for use between two hubs or switches). Each computer requires a Network Interface Card to connect to the network.
0680 - There was no dial tone
This happens with the modems that use Dialup Networking. It's not referring to a normal phone dialtone when using ADSL, but rather the lack of ADSL signal.
Check your ADSL modem first as they generally have an ADSL or Link light which should indicate whether or not an ADSL signal is present.
Plausible Solutions:
- If it's a wires-only installation and the activation date hasn't passed, this is normal. Once your ADSL light goes solid green, the line should work.
- Check your wiring and use of micro-filters. Try unplugging all telephones and running the modem from the master socket.
- Unscrew the face plate on the master socket and use the test socket inside. This will bypass any alarm/extensions on your line, giving you a more accurate response.
- Do remember that Sky and Sky+ boxes count as a telephone, since they have built in dial-up modems, and therefore must be filtered.
- If the connection has been previously working, check everything is plugged in correctly and then contact your ISP.
If you cannot move your hardware to the master socket (for obvious reasons), go down to your local electrical store and purchase enough RJ-11 to reach from the ADSL modem to the micro-filter on the master socket.
0721 - The remote computer did not respond
Also applies to Error 650/718
Although predominately this can be narrowed down to either incorrect provisioning / engineering work at the exchange, there are a number of solutions to attempt before screaming at your ISP:
- Wait 15 minutes, reboot, retry
- Disable antivirus/firewall software, retry
- Uninstall / reinstall modem, retry
- Uninstall / reinstall DUN, retry
Check there is no noise on the line as well and ensure that your equipment is connected correctly and that there is a micro-filter on each socket.
One factor that you should never overlook is the possibility that the end user has previously installed AOL software on their machine.
AOL provides it's subscribers with it's own network adapter and connection software which will overide any existing Dialup Networking Software, preventing the end user from connecting stably.
Other culprits include (but are not limited to):
- Bluetooth Technology
- Virtual Private Network (VPN)
- Spyware/Malware
However, there is really only a finite amount of troubleshooting you can perform with error 0721 and chances are, if it still isn't working, you will need to report it as a generic fault.
FAQ
What are the settings for ADSL in the UK?
Typical settings for ADSL in the UK are as follows:
- VPI = 0
- VCI = 38
- ADSL Modulation = Auto, G.DMT or ANSI T1.413
- Encapsulation Mode = PPPoA - RFC2364 VC-MUX
- Authentication = CHAP
- Service name = Home 500
What number should my modem dial?
You won't need to put in a number for the modem to dial, but if you are asked, simply enter 0.
What does it mean if the USB light is flashing on my modem?
If the USB light is flashing, it means that the modem is not communicating with the computer. This can be caused by incorrect installation, a faulty USB port or even a faulty modem.
What does it mean if the ADSL light on my modem is red/flashing?
This usually means that the modem has not synchronised with the exchange. See Error 0721.
I'm connected but I can't view any websites
- If you are behind a Firewall, try disabling it.
- Make sure that "work offline" is not ticked in the file menu in Internet Explorer.
- Make sure Internet explorer is not set to "never dial a connection" in the Internet Options menu.
- Make sure your Internet Security is not set too high.
- In Internet Options, make sure you are not set to use a proxy server.
Also, if the router or modem claims you are connected but webpages such as http://www.google.com aren't working, try accessing them via their IP address (in this case it's http://66.102.9.99).
If this works, then you have a DNS problem, most likely the wrong DNS servers are specified. Check which DNS server IP addresses are specified in your computer's TCP/IP network configuration.
If you are using a router try adding the actual IP addresses for your ISPs DNS servers. Contact your ISP if you are unaware of these values.
My voice line is 'noisy' after installing ADSL?
Try disconnecting your modem to see if the noise disappears. If yes, you may have a faulty micro filter, or a technical issue with your phone line.
If no, any number of factors may be creating noise. Contact your ISP who will be able to submit a fault report to BT.
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