Kitz Forum
Broadband Related => Telephony Wiring + Equipment => Topic started by: vhooker on March 16, 2012, 03:35:01 PM
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I have two BT phone lines running in to my house. One line is used for business purposes and also has my broadband service operating on it, the other is a line dedicated for other purposes, this line does not have a broadband service operating on it. I have a need to re-route some of the phone wiring in the house, and one of the points to which the two lines need to be run currently has a 6 core (phone) cable run to it - but is not in use yet. I believe that only three cores are really needed to operate a phone so I would like to ascertain if I could utilise this six core cable to run both lines through using three cores for one line and three cores for the other, terminating each trio of cores on seperate BT sockets. Because of building work that has been carried out I can not really run an additional cable to intended location. I have seen a lot of discussions on various forums about interference induced by bell wires etc and so would like to understand if supporting the two phone lines over a single physical cable is likely to cause me problems. The cable run would be about 10m from the master socket. Although I am in a rural location and live quite away from the exchange my broadband service has been pretty could and the sync speed is normally about 7Mb. It would be a bit of a pain to just give it a go to see what happens (and find it does indeed have an adverse effect) so I would like to ask if there is anyone there that could offer some insight if this would be a workable proposition that would not degrade my broadband service by very much. Thanks in advance for any help and advise.
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Basically there is no issue with running 2 lines over standard (3 pair or 6 core) Standard Twisted Pair. My only concern is that you mention running them over an extension cable which will be braided and untwisted. Could you clarify?
Cheers
Rich
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I believe that only three cores are really needed to operate a phone
No, only 2. (2 and 5 in a standard socket)
Make sure each line is using a twisted pair - e.g. white/orange with orange/white.
The 3rd wire you are thinking of (3) is the "bell wire" and is redundant for modern phones. The signal on it is created by the master socket but can be omitted. If you do have an older phone that requires it then a plug-in ADSL filter local to the handset will recreate it anyway.
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I believe that only three cores are really needed to operate a phone
No, only 2. (2 and 5 in a standard socket)
Make sure each line is using a twisted pair - e.g. white/orange with orange/white.
The 3rd wire you are thinking of (3) is the "bell wire" and is redundant for modern phones. The signal on it is created by the master socket but can be omitted. If you do have an older phone that requires it then a plug-in ADSL filter local to the handset will recreate it anyway.
It would depend upon whether its being run to a master or secondary socket i.e. a socket with a bell capacitor or not.
Normal convention is:
pair 1 = white/blue blue/white
pair 2 = white/orange orange/white
pair 3 is white/green green/white
But I'm just splitting hairs ;)
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Hi VHooker,
To avoid any possible difficulties with the broadband signal I would try to install its master socket as close as possible to the building entry point with the broadband modem connected via a dual socket filter faceplate (SSFP in BT Speak) and then run any extensions you wish down your 3 pair cable.
Kind regards,
Walter
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It would depend upon whether its being run to a master or secondary socket i.e. a socket with a bell capacitor or not.
Not really.
It has been commonplace advice in broadband circles for some years now to totally disconnect the bell wire throughout your wiring.
As noted above it is not normally required and can be recreated/simulated if it really is required for an "older" phone.
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http://www.kitz.co.uk/adsl/socket.htm
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This is all assuming that the terminating socket has a capacitor surely? If its a secondary I.E. a 2/3a or 3/3a or 4/3a and the handset is a POT then how will it ring or have we been supplying "dodgy" analogue handsets for the last 20 years?!! (Quite possible)
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Read my posts. ;)
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Thanks to every one for your help. I have to say I was really surprised how quickly people responded, so thanks everyone. I am going to try and setup the new wiring and sockets next week and see how it goes. I was just really hesitant about doing it as moving the line with the broadband on it is going to be a pain and I use that line almost all day for business. If it went wrong it would have been a major inconvenience for me. The responses have been very useful and have given me the confidence to go ahead with the planned move now. Thanks everyone.
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Good luck, let us know how it goes.
And remember to keep the main signals for each line on it's own (colour-matched) dedicated twisted pair.
If you do decide (I wouldn't though) to connect up the bell wire(s) then use the 2 wires in the 3rd pair for that - mostly they'll be inactive anyway and shouldn't interfere with each other.
(though they will BOTH interfere with the broadband AT ALL TIMES by acting as radio aerials >:D )
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I have two BT phone lines running in to my house. One line is used for business purposes and also has my broadband service operating on it, the other is a line dedicated for other purposes, this line does not have a broadband service operating on it. I have a need to re-route some of the phone wiring in the house, and one of the points to which the two lines need to be run currently has a 6 core (phone) cable run to it - but is not in use yet. I believe that only three cores are really needed to operate a phone so I would like to ascertain if I could utilise this six core cable to run both lines through using three cores for one line and three cores for the other, terminating each trio of cores on seperate BT sockets. Because of building work that has been carried out I can not really run an additional cable to intended location. I have seen a lot of discussions on various forums about interference induced by bell wires etc and so would like to understand if supporting the two phone lines over a single physical cable is likely to cause me problems. The cable run would be about 10m from the master socket. Although I am in a rural location and live quite away from the exchange my broadband service has been pretty could and the sync speed is normally about 7Mb. It would be a bit of a pain to just give it a go to see what happens (and find it does indeed have an adverse effect) so I would like to ask if there is anyone there that could offer some insight if this would be a workable proposition that would not degrade my broadband service by very much. Thanks in advance for any help and advise.
If we think about it logically, your two circuits travel down the same cable for miles from the Exchange, along with hundreds of other circuits. It wouldn't matter a jot for another 10m of extention cable.
I think Ottersnose has got the wrong end of the stick. If ,as you quote, the extention cable is 6-core, then it won't be braided and untwisted. It will be solid-core and fully twisted. As mooted, leave the bell-wire off, if the phone is quite old just plug an ADSL micro-filter in the socket. They have their own 'ringing capacitor' installed inside them.
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On a slightly pedantic note, the bellwire's purpose is not just to provide a 'ring' signal for old POTS phones, it also served the very important role of stopping these old POTS phones from interfering with one another when there were multiple extensions on a single line.
Without the bellwire, pulse dialling can be mistaken by the phones for a ring signal, and indeed it was a common fault in days of old when people hooked up (illegal) diy extensions, wrongly connected or using imported phones, when somebody dialled a number on one phone, the other phones would go 'ting-a-ling' in time with the dialling. The ring signal generated by the microfilter does not address that aspect of the issue.
I'm not suggesting that is likely to be a problem (does pulse dialling even still work?), and I encourage bell wire removal, but I thought it may help if anybody is curious as to why old-fashioned phones didn't just generate their own signal in the first place.
- 7LM
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On a slightly pedantic note
Not at all pedantic, but totally accurate. BUT ( see below)
Somewhere in my "archives" I have the instructions on how to rewire the internals of a 1950's/60's phone to work correctly with the "new system".
The significant difference was that the "signalling mediation" for want of a better phrase was changed from being a shared responsibility between multiple phones on the line to the "new" master socket (which didn't exist before) ;)
This then evolved in due course to the NTE5A etc etc.....
Most actual problems came from mixing equipment from pre- and post- master socket standards, not the bell wire as such (though this did give either non-ringing or ringing-while-dialling symptoms)
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(does pulse dialling even still work?)
AC9 signalling (a.k.a. loop-disconnect dialling, a.k.a. pulse-dialling) does, indeed, still work. I have a 300-series telephone, which is not quite as old as me, connected to my line. I tend to use it for receiving calls only, when I am sitting in the armchair with that telephone next to it.
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Thanks 7LM, you've just brought back fond memories of the old fault report code, 'Bell-tinkling'. ;D
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Ever had to fit a Thermistor? :D
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Funnily enough, I haven't. The newer Sys X and Sys Y Exchanges were being installed when I was first taken on with BT. I worked as a 'Sparky' for my first few years, so when I eventually moved to the dark-side, dial-phones were a thing of the past. ;D
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Funnily enough, I haven't. The newer Sys X and Sys Y Exchanges were being installed when I was first taken on with BT. I worked as a 'Sparky' for my first few years, so when I eventually moved to the dark-side, dial-phones were a thing of the past. ;D
Did you get to attend any pow-pows at the Adelphi, Liverpool? There were regular training seminars held at the Hotel on Sys X/Y installation for GEC/Marconi/Plessey engineers. Legendary shindigs, so say the few who survived them!
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Ever had to fit a Thermistor? :D
No prizes for guessing another couple of (identical) items that I have in my grotto . . . ;)
I held (and still hold) the opinion that a thermistor was (is) a device of "last resort". By that I mean that 200-, 300- & 700-series telephones should be wired properly when more than one device was (is) connected to the line. ;D
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Funnily enough, I haven't. The newer Sys X and Sys Y Exchanges were being installed when I was first taken on with BT. I worked as a 'Sparky' for my first few years, so when I eventually moved to the dark-side, dial-phones were a thing of the past. ;D
Did you get to attend any pow-pows at the Adelphi, Liverpool? There were regular training seminars held at the Hotel on Sys X/Y installation for GEC/Marconi/Plessey engineers. Legendary shindigs, so say the few who survived them!
Ha ha, I can well imagine the 'wrap party' when comms engineers are involved. ;D :drink:
I have been to The Adelphi for a couple of 'Meet & Greets'. The main one was when Openreach was on the threshold of being fully launched. I was 'acting up' for my boss at the time and was sat amongst the upper tiers of management. The ones that kind of write their own pay-checks. I actually got to say 'Hi' to our then CEO (Steve Robertson), and felt like a teenager meeting their pop-idol for the first time !! I was by no means infatuated with the guy, he just had a presence about him if you know what I mean ???
Anyhows, after the presentations and lunch, it was off to Albert Docks to unveil the new Openreach van liveries and the engineering communities workwear. Our original outfits were actually purple, and we looked like a team of pimps !! It didn't last long before we reverted back to blue.
For those who aren't aware, the Sys X and Sys Y Exchanges saw the demise of Strowger, Crossbar and the two TXE types (TXE2 and TXE4). The floor space created once the old stuff was removed was immense !! That was a lot of my job at the time, de-commissioning large/medium bus-bars and other 240/415V electrical gear. I know I hark on about BT now and again, but it really was a pleasure coming to work back then !!! :)
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Just chanced on this very interesting thread, and feel impelled to offer a couple of clarifications.
AC9 signalling (a.k.a. loop-disconnect dialling, a.k.a. pulse-dialling) does, indeed, still work.
AC9 was a 1VF (2280Hz) signalling system used on trunk circuits between Strowger GSCs. The filtering wasn't perfect, hence the faint 2280Hz 'beep' on called party answer - still heard in radio plays long after the system's demise.
I held (and still hold) the opinion that a thermistor was (is) a device of "last resort". By that I mean that 200-, 300- & 700-series telephones should be wired properly when more than one device was (is) connected to the line. ;D
Agreed absolutely! Their only legitimate use was in 'shared service' (party line - not WB900 or DACS) installations, where it was the only way to prevent bell tinkle.
I know I hark on about BT now and again, but it really was a pleasure coming to work back then !!! :)
Hark back all you like AFAIC, fascinating stuff. It was indeed a real pleasure back then.
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Just chanced on this very interesting thread, and feel impelled to offer a couple of clarifications.
AC9 signalling (a.k.a. loop-disconnect dialling, a.k.a. pulse-dialling) does, indeed, still work.
AC9 was a 1VF (2280Hz) signalling system used on trunk circuits between Strowger GSCs. The filtering wasn't perfect, hence the faint 2280Hz 'beep' on called party answer - still heard in radio plays long after the system's demise.
Oops . . . :-[ b*cat has, indeed, typed a nonsense. Many thanks for correcting me, 4C.
There are so many codes, acronyms and what-nots filed away in the wet-ware, that once in a while the wrong one issues forth. :-\
Now my current problem is that I cannot recall the correct term for loop-disconnect signalling nor am I sure if the current day dual-tone, multi-frequency signalling is MF4. :help:
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There are so many codes, acronyms and what-nots filed away in the wet-ware, that once in a while the wrong one issues forth. :-\
Now my current problem is that I cannot recall the correct term for loop-disconnect signalling nor am I sure if the current day dual-tone, multi-frequency signalling is MF4. :help:
;D Yes indeed - telecommunications and computing et al sometimes seem to comprise mainly acronyms and codes.
It's all a long time ago now, but I can't recall any special name or code for pulse dialling other than 'loop disconnect', abbreviated to 'LD'.
You're right about MF4, but I had to check here (http://www.britishtelephones.com/pwover1.htm) to be sure. :-\
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Thank you for providing the confirmation, 4C.
The site, to which that link referred, is known to me but I had never read that particular page. It triggered memories of the concept of phone phreaking and reminded me that -- somewhere in my grotto -- I have a file with copies of a series of articles that the magazine New Scientist published on the topic, dating from the early 1970s.
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Ah, phone phreaking - those were the days. 8)
I could relate some personal experiences on that subject, if anyone's interested; I don't think they can touch me for it now. ;)
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I could relate some personal experiences on that subject, if anyone's interested; I don't think they can touch me for it now. ;)
Yes, I remember some students back in the late sixties who actually PAID for their phone calls........ :-X
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Yes, I remember some students back in the late sixties who actually PAID for their phone calls........ :-X
I assume others are aware of the "back-dialling" that could be performed with the Push button A / Push button B telephone boxes? ::)
Then there was the "exhaustive" dialling of all possible 1xx-level codes, to see what other legitimate (and some unofficial "engineering") numbers were active. I had already been told about the faults-man's ring-back (174xxxx) by a GPO Engineer in the early 1960s and had read about the subscriber's automatic line-tester (SALT, 175xxxx) in the POEEJ, so I was not surprised to discover the test/trace oscillator (176xxxx) by my early "exhaustive" dialling 1xx-level codes. I last used those test codes back in 1994 on a Strowger exchange in the London Director area.
I think it was in the 21st century when I was first told of 17070 . . . :-\
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Crikey ...... SALT (Subs Apparatus Line & Test), wonder if this is still active ? ;D
The main 'phreak' of the time was 'tap dialling'. In other words, one just needed to tap the switch hooks in a consistent manner, for the required number, with a slight break between numbers.
For eg - for 999 you would quickly tap down on the switch hooks nine times, then wait approx a second and then start tapping your next number etc etc .................
There was a period (way before mobile phones), where as engineers we were all given a 'pre-dial' code that was input before the number you were actually ringing. This ensured it was a free call.
They have the same engineers numbers for mobile networks nowadays.
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'pre-dial' code
I remember some of those that would even allow international calls (to countries where direct dial was possible). :angel:
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I assume others are aware of the "back-dialling" that could be performed with the Push button A / Push button B telephone boxes? ::)
Aware, yes, but I was more of an inveterate 'tapper', with quite a high success rate. It helped that the dial could be used for '9' and '0'.
Another favourite wheeze was dialling into the GSC and back out, then dialling '0' for the operator. This meant that the call would show on a white light (ordinary line) instead of a red light (coinbox). The requested call would be placed, and ticketed to the coinbox number. >:D
In the days before the 'cuckoo' beeps were introduced, I'd sometimes call my mate at a coinbox and reverse the charge. ;D
But for me and many others, phreaking was about phun, not prophit. Like exchange hopping for eighty miles across country, just because one could - a conversation wasn't possible. Then when the called party cleared, there was the sound of selectors dropping out one after the other, getting louder each time.
Then for a bit of entertainment at lunch time, I'd dial into the GSC, back out, in again, back out, etc etc, just to hear the clicking of the relay sets, and the cascade of selectors when released. Of course, if the chain didn't complete, that would provide an investigation for later in the day. :)
Crikey ...... SALT (Subs Apparatus Line & Test), wonder if this is still active ? ;D
Not that I'm aware of - 17070 seems to cover everything on the various options, and more.