Improving your BT Line based Broadband Speed - Isolate the Bellwire!

The original web article from which so many others took their inspiration!

1. Introduction
2. Symptoms.
3. Diagnosis.
4. The Science.
5. The Cure.
6. BT's Solution.
7. ADSL Killers.
8. Other Research.
9. Go straight to the fix.

Printing this article: if it does not page properly, try the Opera 9.5 browser which seem to behave better.This page is also available as a pdf document.

1. Introduction

THE FOLLOWING CURE LIFTED MY BROADBAND SPEED FROM 461K TO 2.8MEG - SIX TIMES THE SPEED!!

Even if your phone extension sockets are unused, those extensions can still generate electrical interference from the bell-wire down the BT line and reduce your exchange profile speed setting.

If you have no bellwire interference, this approach will in most cases do no harm even if there is no improvement, and will protect from future RF interference.

I receive many emails telling me how the bellwire fix has doubled, even quadrupled broadband speeds, and most bizarrely, recently a case where interference from a gym treadmill in the person's garage disconnected and reset the hub whenever it was used. Disconnecting the bellwire fixed the problem and also quadrupled the ADSL speed. Many cases can be seen reported on the Home Hub Forum


Only proceed if...

• You have a standard NTE5 master socket with a removable lower half
• You have telephone extensions wired in the house

If you have the split ADSL/Phone Master socket, proceed only out of interest, but leave the bellwires intact.
Personally I find that kind of ADSL/Phone twin socket unhelpful as it does not allow the modem to be plugged into extension sockets. This Bellwire fix will allow you to plug the Hub into any extension in the house without problems.

If you want to cut the science and go straight to the fix look here

2. The Symptoms

BT Modems work with the exchange equipment to determine the fastest stable speed that the exchange is happy with. It is optimised to give the best speed considering the signal errors received.
This optimised speed is known as your "IP Profile" speed at the exchange.

The "Downstream" speed displayed on your hub pages is the Synchronisation (Sync) speed and is the initial speed negotiated with the exchange equipment when you first connect the hub, based on their database information and line condition.

(For more on speeds see here.)

Typical symptoms of electrical noise on the extensions when using the BT home hub are when Sync speed starts high after reconnecting the hub to the DSL line, then gradually slows down to maybe a half or a quarter of that speed after a couple of days. Your IP Profile speed (see below) may stay low, and will only improve if you can fix the noise problem.

To help you diagnose speeds, BT supply two websites. Firstly the Speedtester Siteis recommended to display the IP Profile and to measure Actual speeds from exchange to hub. This must be run using Internet Explorer for best results. There is also an "expectations site"to tell you what to expect at your address.
You MUST use your POSTCODEin that expectations site. If you use your phone number, as an existing customer you will more likely get your current IP profile, and if you do have a problem locally you want to know what you COULD be getting rather than what you ARE getting - hence use POSTCODE!

If you compare the two sites, and the Profile speed is a lot less that the Postcode Expectations speed, (say at leat 30 percent less) then suspect either

• A noisy house installation
• A bad BT line

Be assured that this speed adjustment by the ISP is essential - the alternative to managing the speed is an unstable connection. Whet you need to do is to find out why.

3 Diagnosis

(the "Clean Socket" test)

If this test shows no improvement after three days, your wiring is probably not the problem.
First check you are not using P2P or downloading too much (BT Option 3 caps at around 50 - 100Gb a month, but that figure is not published in the Fair Usage Policy (FUP).

If you are certain you have not been capped under the FUP, having done the Clean Socket test to eliminate your house wiring you are then well armed to tell BT it's their problem!

In order to see if your house wiring is affecting your speeds you should go to the master socket i.e. the first white socket in the property with BT or Openreach printed on it. (If it says Openreach you may well have one of the new bellwire filtered sockets - see later).

This is the NTE5 master socketfitted up to 2007. House phone extensions are wired into the removeable lower part of the socket to which the homeowner is allowed to remove and add extensions.
Remove the lower half of the socket and let it hang. if you have hard wired extensions they will be connected to this removeable part.

Plug a BT ADSL filter into the socket in the remaining part of the socket still attached to the wall. Plug one phone into the filter, and the Home Hub's ADSL (Broadband) lead into the other socket in the filter.

Leave the socket like this for THREE DAYS. Then repeat the speed tests and see if your profile has improved significantly.

If the IP profile is much better at the end of the 3 days, you have a problem with your extension wiring, and the most likely culprit is the bellwire.

However the main twisted pair can also pick up interference so you should also check routing of the extensions and avoid mains wires and equipment such as microwaves, TVs and other radio devices like DECT phones.

Having a home hub, you are lucky in that you can use Wi-fi from the Hub in its temporary position by the master socket, but if you have only ethernet cable or USB, DO NOT EXTEND THE PHONE OR CABLE for this test, MOVE THE PC NEARER THE HUB!! There is no point in eliminating the extension wiring then adding more flexible extensions which contain their own bellwires!

4 The Science.

At the Home Hub Foruma contributor codenamed Bramshot told me his story of the BT engineer who removed his bellwire and the subsequent hike in speed. More web research I did using Google and Yahoo also came up with the theory that the "bell-wire" is the cause. (See other citations at the bottom of this article).
The Bell Wire is the third wire on terminal 3(usually orange/white) used in the standard BT extension wiring that was introduced in the early 1980's when DIY extensions became legal, and BT relaxed their monopoly on supply of phones.
From under the road or along a telegraph pole, your house is served by just TWO wires. This third "bell-wire" is generated by the BT master socket and enables actual bells on old type phones to ring using the 50 volt AC ringer signal. Modern phones have electronic ringers which do not need the bell wire. Its other function is to stop other bells tinkling when rotary dials are used, and it was always known as the "anti-tinkle wire" in the 1980's when we all experimanted with DIY extensions.

On standard domestic phone with broadband and individual ADSL filters you don't need any wires apart from the two main conductors on terminals 2 and 5, usually blue/white and white/blue. This is because ADSL filtersisolate the phones from the bellwire and recreate the function in the filter. This makes the bellwire totally redundantin a broadband enabled domestic phone system.

Leaving the bell wire in place creates a huge long antenna which picks up radio frequency (RF) interference all over the house. The two conductors that carry the voice and DSL signals are a "randomly twisted pair" which carry current in opposite directions (from master socket to extension socket and back again) so the RF interference cancels itself out. The unpaired bell-wire cannot cancel out the RF.
There is also another redundant (white/orange; terminal 4) wire which has never been used by BT on simple domestic wiring. Best to disconnect this too to avoid confusion.

5. The DIY Cure.

The cure is to disconnect all wires in terminals 3 and 4 at the NTE5 master socket.


On the Master socket disconnect the wires that are connected to terminal 3 of the removable face plate. May as well take the white/orange wire from terminal 4 too - it is unused anyway. Look herefor details.

If you have an old plain BT master socket you could snip out the bellwire(s) from the back of the faceplate that go to the extension sockets, although this is by law supposed to be done by BT. The bellwire carries no current so I leave it to your conscience.
You are not supposed to fiddle with the two BT wires coming from outside, and there is no need to anyway, unless you want to fit your own replacement NTE5a socket. Again, it's illegal to do so, but it's not rocket science. Provided you don't allow the incoming wires to touch each other or to touch anything else metal, you will do no damage, but again it's illegal in the UK so I can't suggest fitting your own master sockets either - it's up to you, and if you can find a UK supplier.

The result is that throughout the extension system, you leave just TWO WORKING CONDUCTORS on terminals 2 and 5, (white/blue and blue/white.)

6. BT's solution

More recent master sockets labelled "Outreach" rather than "BT", will most probably have the new inductor in the bellwire circuit. I tested one of these with my bellwire reinstated. My IP profile remained at 3000k and the sync speed dropped only minutely from 3684 to 3584kbps , so I can confirm that the new faceplates do work almost as well at reducing bellwire RF noise as the bellwire being cut.


The photograph shows the difference between the new (LEFT) and old (RIGHT). The new one has a cylindrical bulge in the lower removeable plate that houses the inductor.

Unfortunately it may cost you for an engineer visit but ask your BT sales helpdesk.


The way the original master seems to have been modified is shown below. the inductor blocks high frequency interference.


iPlate
They also have a new idea - the "iPlate" or Interstitial Plate which fits between the old type frontplate and the backplate Thanks to this site http://www.hmmm.ip3.co.uk for the pics I stole and reproduce here.


The iplate is believed to comprise a choke on the bellwire (3) plus some sort of common mode choke on the speech wires (2 and 5) to reduce RF interference on the speech wires as well as the bellwire.

7. THE ADSL KILLERS!

The pictured "DIY Extension Cables" are still on sale in "good hardware shops" but are capable of killing your ADSL speed unless you have an "iPlate" or bellwire-filtered master socket. The bellwire fix will probably not help you if you have any of these killers in circuit.

Quite simply the 15m of bellwire plugs straight into the extension socket and cannot be isolated without a scalpel and giving the wire a vasectomy.
ONLY use proper round phone cable with loose random twisted solid core wires and properly wired to the master socket faceplate (or extension socket backplate if on a daisy-chain) using terminals 2 and 5 only.

8. Other References

Master Socket (diagrams copied from WPP site)

See how the bell-wire on terminal 3 connects to BT "B" via the 1.8 mf capacitor which has a low impedence to higher frequencies - i.e. a capacitor passes high frequency noise through as though it was a conductor.

Standard domestic BT wiring - Disconnect wires at X.

DISCONNECT ORANGE CABLES ON TERMINALS 3 AND 4!!

Simply cut them or pull them out of the faceplate terminals. They carry no voltage and are quite safe to cut individually. Leave only the Blue/White wires on 2 and 5. For details see here

That will reduce RF interference to a minimum and increase your stabilised throughput speed.

More supporting data I found since my own experiments can be found on Doug Rice's website