Guide to Self-Install

This section provides you with some general information on self-install ADSL, including some facts about microfilters and where to fit them.

The BT Master Socket

In the UK, the majority of people with BT telephone lines have a master socket called an NTE5. This is a white plastic square with a removable faceplate on the lower half. The master socket marks the boundary between the telephone wiring provided by BT (which you should not modify) and your own internal wiring. If you remove the NTE5 faceplate, then you will find a telephone socket behind that is connected directly to the incoming BT line - the action of removing the faceplate disconnects all your internal wiring. This is a good way to find out if any problems you have with your telephone (or ADSL) service are being caused by your internal wiring.

Usually, your house will have four wires (two twisted copper pairs) coming into the master socket from outside. Only one pair is required to provide a single telephone line. The second pair is there to provide a second phone line if you need one. At the master socket, the two wires for your first telephone line are converted into three wires, and it is important that all extension sockets are connected with all three wires otherwise your telephones might not ring correctly.

Extension Sockets

Most people do not have only one telephone socket and extension sockets are used to provide access to telephone services in other parts of the house. These extension sockets are wired from the master socket and as mentioned above, it is important that all three wires are connected. (Usually four wires will be connected but the fourth wire plays no active role).

Centralised Filter Installations (the Faceplate Splitter)

When BT first started to deploy broadband services in the UK using ADSL it was necessary for a BT engineer to visit your home to do the installation. This involved putting a new faceplate on the NTE5 master socket that incorporated a splitter for the ADSL service. The new faceplate had two sockets on the front, one for the telephone and one for the ADSL modem. The faceplate also provided filtering for all the connected extension sockets.

With the ADSL faceplate fitted it is only possible to connect your ADSL modem to the master socket, so if you wanted to connect a PC in a different room you needed to fit an ADSL extension cable.

However this kind of installation does have advantages - for example it looks neater than using individual microfilters, and it helps prevent noise on your internal wiring interfering with your ADSL connection. You can now buy faceplate splitters as well as microfilters from The Broadband Zone and see some further information here.

Microfilter Installations

The engineer-installed version of ADSL is no longer the norm in the UK (although it has been re-introduced as a free service on new ADSL installations where the line is subject to high attenuation and noise). Instead, you do the installation in your home yourself. This involves connecting your ADSL equipment (i.e. modem or router) to your telephone line and fitting "microfilters" (also referred to as "splitters", "micro-splitters" or just simply "filters") in line with any telephones or similar devices.

Microfilters usually have one BT-style plug (to connect into your wall socket), one BT-style socket (into which you can plug your telephones) and one smaller RJ-11 socket (into which you can connect your ADSL modem). The RJ-11 lead that usually comes with your modem is in most cases exactly the same kind of lead that you would use for a dial-up modem. If it has RJ-11 at both ends then connect between your ADSL modem and the port on your microfilter. If it has a BT plug at one end then it can be connected directly into the telephone socket (but you must not have any telephones on that same socket).

Using Different Extension Sockets

With self-install and microfilters you are no longer restricted to using just the master socket for connecting your ADSL modem. It can connect to any of your telephone extension points. The important things to remember are:

• Any telephones (or fax machines, or Sky digital set top boxes, or 56k dialup-modems, or caller-display devices - or any other such device connected to the telephone line) must go through a microfilter
• The ADSL modem itself can connect straight to a telephone socket without a microfilter if there is no other device sharing that same socket.
• You cannot connect more than one ADSL modem to the same telephone line at the same time. Unlike conventional dial-up modems, when powered-up ADSL modems are constantly trying to connect to the telephone exchange and if you connect more than one they will interfere with each other.

How Many Microfilters?

In simple terms, you should fit a microfilter in line with any telephone (or device that uses the normal telephone line). So you need to connect every telephone, fax machine, Sky Digital set top box etc through a microfilter. Remember that if you continue to use a dial-up modem that will also need to be connected through a microfilter.

However, it is possible to use less microfilters by modifying the way your telephones are wired. For example, a single microfilter could be used to filter all the phones on an extension lead. The important thing to remember is that on the "telephone" side of the filter, there will be no ADSL signal, so you cannot connect your ADSL modem after the filter. As mentioned above, you can also connect your ADSL modem directly to a socket with no telephones as shown in the diagram.