DSL Modem working on a socket thats not the main one

LeperKing

Hi

I'm trying to get my dsl modem working on the socket upstairs but the dsl light stays blank (BT Modem) is there any suggestions of how I could get this going? (I have the dsl filters on all the other sockets) It works fine downstairs at the main telephone socket.

Thanks,
LK

quazzy

From what I remember of my eircom BB days the BB is not guaranteed to work on extension sockets in any house.

Its only guaranteed on the main socket.


Maybe the scoket is banjoed and needs replacing.

ethernet

It should work on any extension as long as there's a DSL signal there in the first place [and a microfilter used].

The problem may be due to the way the extensions were connected -- in some cases [to cut costs and avoid the use of microfilters on every extension where it wasn't throught DSL would be used], the cable rooted from the master socket [i.e. the one eircom, ad hoc, installed with their logo] has already passed through a microfilter ... except from its PHONE output, meaning there's no DSL signal.

May may want a professional to check this out if you're not up for investigating yourself.

LeperKing

Filters inbuilt into the house wiring? Does that exist? The house is ~25 years old. So I'll get an electrician to probably just rewire the telephone sockets.

LK

incisor71

If it's properly wired, it won't matter one jot which phone socket you use for the DSL modem. Eircom don't supply phone sockets with inbuilt DSL filters (although if you have an alarm system the story may be a little different - refer to here)

In the simplest case, the two main things to check for are (1) the first socket in the chain, i.e., directly connected to the patchbox from the outside cabling, should be a master socket with a surge arrestor, and (2) any extension sockets, which are usually wired in parallel, should not be master sockets nor have surge arrestors.

Another thing to watch out for is that proper Cat-5 twisted pair cabling is used for all the wiring, not the thick chunky grey/white stuff used up to the early 80s.

lucernarian

incisor71 wrote:

If it's properly wired, it won't matter one jot which phone socket you use for the DSL modem. Eircom don't supply phone sockets with inbuilt DSL filters (although if you have an alarm system the story may be a little different - refer to here)

In the simplest case, the two main things to check for are (1) the first socket in the chain, i.e., directly connected to the patchbox from the outside cabling, should be a master socket with a surge arrestor, and (2) any extension sockets, which are usually wired in parallel, should not be master sockets nor have surge arrestors.

Another thing to watch out for is that proper Cat-5 twisted pair cabling is used for all the wiring, not the thick chunky grey/white stuff used up to the early 80s.

Eircom do supply those special sockets, though it's only used for business engineer installs AFAIK (apart from the phonewatch installs). But it shouldn't be too hard to obtain them. If you see an eircom van at the side of the road or whatever, thalk to the engineer. They're grand with giving someone a master socket if they asked for it, I'm sure they would also oblige if they had an ADSL socket aswell.

The extension sockets should really be wired parallel, and an engineer told me that it doesnt really matter these days if a master socket is used as an extension socket. The new sockets are designed so that all the sockets in the house are protected by the first master socket's surge arrestor.

The wiring need not be Cat5 - the current eircom spec of CW 1308 2 or 3 pair wire should do the job. But the grey and white twisted pair is a no-no for DSL - it's made of aluminium as opposed to copper.

You're right though, if everything's wired up to spec DSL should work equally well at any of the sockets.

P.S. The surge arrestor in them master sockets is a pile of pooh. Completely useless:(

incisor71

To_be_confirmed wrote:

Eircom do supply those special sockets, though it's only used for business engineer installs AFAIK (apart from the phonewatch installs). But it shouldn't be too hard to obtain them. If you see an eircom van at the side of the road or whatever, thalk to the engineer. They're grand with giving someone a master socket if they asked for it

I had to be present at the house when the engineer was installing the new master socket, so I asked him if he had an extension socket and he obliged immediately.

To_be_confirmed wrote:

P.S. The surge arrestor in them master sockets is a pile of pooh. Completely useless:(

Perhaps it's used as a varistor rather than a surge arrestor? The original telephone systems used varistors at the customer end to provide a primitive form of voltage regulation, so that subscribers on long-distance loops (who would suffer greater signal loss due to cabling losses) would receive similar signal levels to those experienced by their near-exchange contemporaries. But I don't know whether that component exists/existed within the phone itself or the wall socket.

Sorry for dragging this kinda off-topic!

ZENER

I used 4 core alarm cable to wire the extensions in my home and all work equally well with DSL. The master socket not only provides a surge protector but also provided a seperate ring signal. Most of the time when called to check why modems don't work is because they're plugged into incorrectly wired extension sockets. Irish spec phones use the RED/GREEN pair. I find that some sockets were wired to allow BT phones (especially cordless ones ) to work - these use the BLACK/YELLOW pair which will not work for Irish spec phones.

ZEN

rogue-entity

I think you are all way off, especialy about the master sockets.

Our house had a telephone since they were "Post and Telegraph" (before Telecom). We had our telephone lines (inside) rewired after we had our old telephone extension system removed. The main wire comes in from the road into a junction box. From their that old 80's grey/white wire runs along the wall to a junction box. From their a wire goes to the a pair of sockets in series for the telephones downstairs. Another wire goes upstairs to my grans room and I wired in another for the DSL in my room.

The sockets with the downstairs phones are that old eircom type before they got those Telecom branded ones that are now the eircom branded ones. The one upstairs for my DSL is just a bog standard extension socket as is the one in my grans room. They all work fine. Only two wires are required to carry the signal and they can be wired in any order. Modern telephones will automaticaly detect the polarity on the wires and just work, but some US modems will not so they often come with an adaptor that looks like a splitter.

Irish telephones use the same two-wire system as they use in the US and it is often the red/green wire. In the UK they use a 3 wire sysem with a third for the ringing signal. That is why they use a special master socket, to generate this ringing signal using a capacitor or something.

I was told that normal telephone extension wires like those you get in the eircom shop cannot carry a DSL signal, so you should make sure it is the twisted pair type that is blue/white on the newer installs and green/brown blue/orange on the older installs. If you have to just rewire it yourself. Run a new cable to the socket you want to use the DSL on, and just connect the two blue wires to the pins labled L1 and L2 and then wire them into the same pins on the extension socket, or the pins going to the red green wires. If the it does not work, swap the wires around at the extension socket and try again. If it still does not work, go back to the master socket and move one of the wires to the Pin called R and then repeat the test above, swapping the wires again (at the extension socket) again if needbe.
Any problems PM me

lucernarian

You are wrong on a number of points.

Irish phones do indeed use the centre 2 wires in leads (red and green). UK phones do not need a third wire any more than an Irish one. Old phones need the third wire so the phone will ring. As in very old phones (pulse dial and the like). If you open any main socket (be it P&T, TÉ or Eircom), you will find 6 IDC or screw connectors labelled S1, S2 and R along with L1, L2 and R. The S sockets are for a second line should you have it on the same cable.

Only difference in wiring between BT and eircom is that in the UK they use the outer 2 wires in the lead (yellow and black).

Tell me, what do you connect your DSL modem to the phone socket with?? Is it not an extension lead? It's not that they are unsuitable for broadband, it's that they are not as good as twisted pair. They are only supposed to be used for short runs like connecting equipment to sockets.

The blue/orange/green/brown wires that the P&T and TÉ at one stage used are not twisted pair, though it is a round cable.

Don't use the R terminal at all unless you have really old phones. I have a PDF document at home which shows the current guidelines for sockets (too big to upload directly).

LeperKing

The plug is actaully a cable coming out of the wall, I'll get the sparks to terminate it properly into a socket.

LK

rogue-entity

To_be_confirmed wrote:

Irish phones do indeed use the centre 2 wires in leads (red and green).

I never said that they didn't but the red/green yellow/black wires are mainly found in US cables or those short leads connecting your device to a phone socket. The actualy wiring is done with Cat5 cable (like that of ethernet) in newer installs as you know already. I have a large reel of this cable and it is what I used when fitting the DSL extension in my room, I connected the extension socket straight into the main junction box where the white/grey wire feeds into. And I connected it on the same side as the white/grey wires.

To_be_confirmed wrote:

UK phones do not need a third wire any more than an Irish one. Old phones need the third wire so the phone will ring. As in very old phones (pulse dial and the like).

Okay, well I was not too sure about that anymore, but the reason for the master socket in the UK was to generate a ring sigal on the third wire IIRC. Irish master sockets were the same as we used the same system as the UK, and we still use the UK ringback tone today.

To_be_confirmed wrote:

If you open any main socket (be it P&T, TÉ or Eircom), you will find 6 IDC or screw connectors labelled S1, S2 and R along with L1, L2 and R. The S sockets are for a second line should you have it on the same cable.
Only difference in wiring between BT and eircom is that in the UK they use the outer 2 wires in the lead (yellow and black).

I know this already, I had a document on all this, but it was missing some of the more up-to-date information.

To_be_confirmed wrote:

Tell me, what do you connect your DSL modem to the phone socket with?? Is it not an extension lead? It's not that they are unsuitable for broadband, it's that they are not as good as twisted pair. They are only supposed to be used for short runs like connecting equipment to sockets.

Well forgive me on this one, I was told by BT that extension cables cannot carry DSL signals very well and to ONLY use the cable that came with the modem. Being niaeve as I was I believed them.

To_be_confirmed wrote:

The blue/orange/green/brown wires that the P&T and TÉ at one stage used are not twisted pair, though it is a round cable.

Don't use the R terminal at all unless you have really old phones. I have a PDF document at home which shows the current guidelines for sockets (too big to upload directly).

The point I was trying to get accross is that some of the suggestions being made were off. What I would do in that situation is this: I would disconnect all the extra wires from the master socket so that only the wire pair from eircom are connected to L1 and L2. I would take a second piece of UTP cable and wire the Blue/white white/blue wires to the other L1 and L2 (or was that S1 S2). And then fit a junction box. Then I would wire each pair of extensions to the junction box as needed. I would make a fresh run from the junction box to the extension for the broadband and wire those same blue/white wires to the red/green wires in the extension socket. That should then work.

lucernarian

rouge-entity wrote:

The point I was trying to get accross is that some of the suggestions being made were off. What I would do in that situation is this: I would disconnect all the extra wires from the master socket so that only the wire pair from eircom are connected to L1 and L2. I would take a second piece of UTP cable and wire the Blue/white white/blue wires to the other L1 and L2 (or was that S1 S2). And then fit a junction box. Then I would wire each pair of extensions to the junction box as needed. I would make a fresh run from the junction box to the extension for the broadband and wire those same blue/white wires to the red/green wires in the extension socket. That should then work.

That would work allright, though I gather that internal wiring is less susceptible to line noise when wired in parallel. What this means is that after the master socket, one cable goes to an extension socket with no junctions etc. Then a cable goes from the first extension socket to the second. Then a cable goes from the second socket to the third extension socket etc.

Solair

The UK and Irish systems are actually quite different.

In the UK, BT has always used a master and secondary system. Eircom has never really used this methodology, although for some reason people keep talking about "master sockets".

In the BT system, the master socket is physically quite large and contains circuitry (including a capicator) that seperates the A/C ringing voltage from the DC signalling voltages on the phone line. The ringing voltage is diverted down a 3rd wire. 3 wires are connected to all of the extension sockets. The idea of this system was to prevent "tinkle" when pulse dial phones dialled out. i.e. when you dialled 3 all the other phones would tinkle/bleep 3 times.

In the UK you'll find that sockets MUST always be wired to a single master socket, usually in a daisy-chain.

The RJ11 North-American modular system was selected here in Ireland several years before BT had even developed its own plug-socket system and has been around for quite a long time. You'll see P&T branded beige RJ11 sockets in some areas dating from the very early 1980s.

The system used by eircom in general didn't require any specific master sockets, every socket has the same circuitry. They could be wired daisy-chained one to the next or in a star formation from a single central junction box e.g in an attic depending on the layout of the house. While each socket does contain a capacitor and can split off the ring voltage, no Telecom Eireann telephone has ever really required this. It was a feature only to be used for backwards-compatability purposes if wiring up particular types of old dial telephones dating from the 60s/70s.

The irish system pretty much always uses 2 wires between all of the sockets and is almost identical, in terms of wiring, to the systems used in North America.

As for the actual network itself. Eircom and BT switching equipment have never really had very much in common. In the UK, the old automatic network was made up of primative "step-by-step" exchanges while in Ireland the bulk of the old network that was automatic was made up of more sophisticated Ericsson Crossbar switches. (These co-existed beside some of the least sophisticated manual systems!)

The UK's digital switches are mostly "System X" a system made by Marconi (formerly GPT - Plessey) as a state funded project in cooperation with the old British GPO (predecessor of BT) with the remainder being Ericsson AXE.

The Irish network is heavily French-influenced. Telecom Eireann did a deal with Alcatel in the early 1980s and bought a very large number of Alcatel E10B digital switches, identical to those that make up the core of the France Telecom network. These have been upgraded over the years and are still pretty cutting edge and provide service to approximately 50% of all lines in Ireland.

The other 50% is switched by Ericsson AXE digital switches, originates in Sweden and is one of the most popular switching systems in Europe.

The eircom network's far more "internationally normal" than the BT network which is full of odd British norms.

e.g. Eircom's Caller ID protocal is compatable with France, Germany and very similar to that used in the USA.

BT uses a totally weird system that signals the caller display data being sent by reversing the polarity of the line!

Also, many modern phones, particularly BT branded ones, will not ring without 3rd wire ringing being present. Hence the reason for those little dongle-like adaptors that contain a capacitor.

As for the wiring.. eircom has made a big change in recent years. There is now a "master socket" of sorts. However, its purpose is not really the same as the BT system. Eircom refer to it as an "NTU", network termination unit. Its main purpose is to provide a clear line of demarkation between the customer wiring and the network. Basically, the socket has a removable face plate. You connect your wiring to this face plate and it quite litterally has an RJ11 plug on the back that fits into a receptical hidden behind it.

The logic of this is that if an eircom engineer calls he/she can simply remove the face plate. Plug in a test phone and immediately know that any fault is in fact in the customer's wiring. eircom no longer have any responsibility for any of the wiring after this demarkation point.

If you have a white socket in your house, similar size to a light switch. Try removing the two screws on the front. You'll find a second socket behind it! This is the test socket. Your extension wiring is connected to screw-terminals on the back of the face plate.

lucernarian

Solair wrote:

The system used by eircom in general didn't require any specific master sockets, every socket has the same circuitry. They could be wired daisy-chained one to the next or in a star formation from a single central junction box e.g in an attic depending on the layout of the house. While each socket does contain a capacitor and can split off the ring voltage, no Telecom Eireann telephone has ever really required this. It was a feature only to be used for backwards-compatability purposes if wiring up particular types of old dial telephones dating from the 60s/70s.

Also, many modern phones, particularly BT branded ones, will not ring without 3rd wire ringing being present. Hence the reason for those little dongle-like adaptors that contain a capacitor.

I always thought that BT phones were identical to Irish phones (or american ones) except for the outer pair being used.

We got a BT cordless phone a few months ago for my late granny which had only 2 wires connected to the UK phone jack?? The adaptor I presumed switched the pair to the centre one. I saw no third wire in the lead but mabye the capacitor is built into the phone?

We wired our sockets in daisy-chain primarily because I thought there was surge protection in them but I found out this was not the case:(. I also understood that there was better noise immunity compared to radial wiring. Is this true?

P.S. I thought BT lately began to use System Y(AXE) more than the older System X because it was technically superior.

Solair

To be quite honest the noise immunity has far more to do with the quality of the cable used (i.e. it should be twisted pair, not straight stuff) and the length of cable runs than it does to the particular topology used. If you straight cable, e.g. the cheapo flat stuff that comes with telephone "DIY" extension sets or use any other type of non-twisted pair cable, you'll find the line will be far more noise prone. Stick with the twisted pair stuff such as CAT 5.

The quality of junctions / connections etc also has a huge impact on signal quality. You need to make sure that any junctions are done with proper telephone grade equipment. It's not unusual to see people using normal 230V electrical connectors in telephone wiring. This can lead to poor quality signals.

As for the UK 3-wire phones. An ever increasing number of phones on the market in the UK are 2-wire as the companies that make them no longer make UK-specific versions and 2 wire phones are happy on the UK network. They all simply comply with TBR 21 (or equivilant) pan-European standards and will even handle the 3 types of Caller ID system used in Europe. However, there are still plenty of weird UK-specific phones and faxes out there that won't ring at all if the 3rd wire isn't "stimulated"

The polarity of the line shouldn't really be at all relevant to a modem / phone. Phones specified for Ireland are supposed to be happy in either polarity.

In most cases in Ireland the ringing voltage is applied "out of phase" across both wires. i.e. the difference in voltage between the two wires is aprox 75V while they're ringing. However, if you were to measure from either wire to ground you'd get aprox half that.

Anyway, for DSL modems the 3rd wire ringer is absolutely irrelevant as they don't have any interaction with the ringing voltage at all. The DSL signal being "piggybacked" on top of the existing analogue phone line.

As for the BT use of AXE and System X.. the bulk of local switches are still System X. AXE was introduced along side it to provide a commerical compeditor to Marconi. System X is pretty much a dead end technology as it was only really ever used in the UK and never exported thus died off. However, BT are stuck with thousands of those exchanges. They'll only disappear when they're no longer any use to BT. There's absolutely no question of them replacing them with AXE simply for the sake of it.

Thankfully P&T/Telecom Eireann picked two switches that became very sucessful. Ericsson's AXE and Alcatel's E10 series. They've been easily upgradable over the years. Nothing worse than having heavily invested in a totally dead-end technology.


On the modem issue: be very careful with some modems as they cross connect the line to other pins in the RJ11 socket on the back. e.g. they may parallel the line on the centre two pins and the outer two. This might allow various configurations of wiring to be used with the modem.

The problem is that some eircom sockets also parallel the line on other pins as well as the centre two. Connecting a modem like this can simply short circuit the line.

The best bet is to use an RJ11 wire that only has 2 terminals in the centre and doesn't make any connection on the rest of them. This will usually solve ALL problems.

This is usually the problem if you plug in your modem and you notice your phoneline goes completely dead. No dial tone and no calls being recieved.

These modems would equally cause total chaos in the US/Canada.
Centre two pins = line 1... next pair = line 2.. next pair = line 3.
NOTHING should really connect between any of these pairs as it can potentially cause total chaos.