Discuss Why does my telephone seem to need four wires? in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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ralphonz

Hi,

According to all my reading telephones only use two or three wires, so why when i try to use any cable with two wires will my phones not work (there is no dial tone).

I'm trying to get an extension lead to go from the master socket to another room. All of the available leads only have two wires in them, and there are many other satisfied customers claiming they work with their phones. I've tried this with two phones and get the same results.

I should also mention that my sky router is connected to the same master socket and the internet works fine.

Any help anyone can provide would be great.
 
2 wires will be OK. connect 2 to 2 and 5 to 5.
 
I've tried it! It won't work, but if i use an older cable with four wires it does work.

I just bought a cable with 2 to 2 and 5 to 5 and i can't get a dial tone with it.
 
Standard connections as stated are 2 & 5 terminal 3 for ring signal on slaves. If you have a exchange system installed the other cabes are used for features within this system.
 
Standard connections as stated are 2 & 5 terminal 3 for ring signal on slaves. If you have a exchange system installed the other cabes are used for features within this system.

Ok, so is it possible that incorrect wiring inside the master socket is what is causing this?
 
Pop it off and have a look, then connect all the other sockets the same, it's only two wires, I have never had any problems, other than customers buying extension cables that are cheap and nasty and don't work from the off
 
I have a really long 10m rj11 extension cable which i could use, provided i get it to work with a two wire cable. Don't need a slave as i only want one phone in the house.
 
Ok, so is it possible that incorrect wiring inside the master socket is what is causing this?

Possible...but is straight forward, bt masters usually have 2 screw terminal maked A & B, which are connected to the main incoming cable. There are then additional idc push terminals to connect extentions from
 
Ok we are not talking abaut masters and slaves now, your saying you are trying to wire a telephone direct into master instead of plugging it into the rj45 socket...!!
 
Are you exceeding your REN allowance?

If you have a number of Analogue devices on your phone line this could be the case as the telephone line will be the power source... if your equipment is digital then it shouldn't be a concern.... typical max allowance is 4 REN before you start getting issues
 
Are you exceeding your REN allowance?

If you have a number of Analogue devices on your phone line this could be the case as the telephone line will be the power source... if your equipment is digital then it shouldn't be a concern.... typical max allowance is 4 REN before you start getting issues

Don't think so. Only other device is a sky wireless router.

I have tried the phone with the ADSL filter and without it (straight into the master socket) and get the same results.
 
Have you just moved to this house?
Has the phone ever worked?

If you plug a phone directly into the Master you should get dial tone AND noise if you have Broadband, if you plug a filter in the Master then a phone in the filter the noise will go .

If not, unplug the master faceplate, all the internal wring should be connected to the faceplate NOT to the Master connections, that should just have B.t's 2 wires on it.
Plug the phone directly into the socket Inside the Master socket.

If you don't get dial tone directly in the Master you have a fault on the line, or your phone service is not enabled.
 
Have you just moved to this house?
Has the phone ever worked?

If you plug a phone directly into the Master you should get dial tone AND noise if you have Broadband, if you plug a filter in the Master then a phone in the filter the noise will go .

If not, unplug the master faceplate, all the internal wring should be connected to the faceplate NOT to the Master connections, that should just have B.t's 2 wires on it.
Plug the phone directly into the socket Inside the Master socket.

If you don't get dial tone directly in the Master you have a fault on the line, or your phone service is not enabled.

Hi,

Thanks for the reply, i've been away for a week.

1. Yes, i have two phones. Both work but ONLY with a 4-core cable and NOT with a 2-core cable.
2. Yes, i've just moved in to this house. There is only one (master) phone socket.
3. I've got sky broadband, it works fine with the supplied filter. Both phones i've tested work with or without the filter but only when using a 4-core cable.
4. I've checked the internal wiring of the master socket. Only the orange and white cables are connected to 2 and 5.


The big question is why do the phones only work with a 4 core cable when everyone keeps telling me they only need two connectors? I have a bag full of BT - RJ11 cables and have tested with all of them. Only cables with four connections will give me a dial tone.
 
I suspect the problem with the 2-core cables is not that they have 2 cores, it's which pins of the RJ11 they connect to. The BT431A plug has the line on pins 2 (B leg) & 5 (A leg), whereas the US convention for phones using RJ11 line jacks was to have the line on pins 3 & 4. Many 2-core cables will be wired 'crossover' to suit such devices, especially modems and fax machines.

If your phone RJ is wired for a 6P4C plug in the UK configuration it probably has its line on 2 & 5. Therefore a crossover cable will not work but a straight-wired one will; your 4-core cables are probably straight-wired.

Have a look at the core colours if you can see them through the slots in the BT plug or bleep them with a meter. You can usually see at a glance which pins are connected at the RJ11.

Lucien
 
Lucien Nunes,

Thank you for that information! It seems to have cleared things up for me.

I have 13 BT-RJ11 cables and all are wired to pins 3 & 4 on the rj11! Even the BT-RJ11 cable I recently bought from ebay UK as a "BT phone extension cable" is wired from 2 & 5 to 3 & 4. I guess this makes all the cables I have useless for UK telephones.

Thank you very much for your explanation.
 

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