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+---- Thread: Telephone systems (/showthread.php?tid=2351)
Telephone systems - Paul - 11 August 2012
Come a major event, the one thing that may keep going is the phone system. Well at least for a while.
Problem is how to access it if all you've got is a telegraph pole with wires on it or a locked building / house with a wire going into it?
CAUTION.
This thread details a way to connect to the telephone system which would be illegal.
This is for information only.
This thread details a way to connect to the telephone system which would be illegal.
This is for information only.
The UK and US telephone system is basically a two wire system. It's dead easy to spline into this in an emergency. Between you and an exchange a telephone essentially runs off two wires.
The 'A' wire and the 'B' Wire.
The 'A' wire sits at Zero Volts to Earth
The 'B' wire sits at -50 volts DC to Earth
There are generally 4 types of drop cables from the pole into a building.
Colour code
The first colour is wire 'A', the second wire 'B'
CW 1406 (No.12)
Pair 1: Orange/White
CW 1411 (No.10B)
Pair 1: Orange/White
Pair 2: Green/Black
CW 1417 (CAD55M)
Pair 1: Orange/White
Pair 2: Red/Grey
Pair 3: Blue/Brown
Pair 4: Green/Black
CW 1378 (No.10)
Pair 1: Orange/White
Pair 2: Green/Black
Between poles and underground systems, cables are normally thicker with more pairs. I'm not going to list them all as they can exceed 100 pairs so concentrate on wires going into a building rather than these main connecting wires.
Each pair is twisted together even on the above cables so if all else fails, pick the wires twisted together in pairs. It's important NOT to mix wires from individual pairs.
For domestic and single line installations, two pairs is normal with
Pair 1 being Orange / White and
Pair 2 Green / Black as a standby.
Again remember that each pair is twisted together.
Interesting information but useless without a simple telephone.
To make a simple service handset.
Buy a cheapy wall mounted telephone (Average price £8) and two small insulated crocodile clips.
Look at the BT plug.
The desired wires go to pin 2 and 5 i.e.
123456
Pin 1 is the opposite side the locking tab.
You'll see one of these colour codes.
Old Wiring YGBR
You need the YELLOW and RED
New Wiring KRGY
You need the BLACK and YELLOW
US Wiring RG
You need the RED and GREEN
Alt Wiring KY
you need the BLACK and YELLOW
Y=Yellow, G=Green
B=Blue, R=Red
K=Black.
Take the plug off and peel back the insulation by 3" and attach the clips as listed.
Then all you need to do outside is to strip back the drop wire and connect to
1st pair i.e. Orange and White.
If it doesn't work, use the 2nd pair Green and Black.
If no joy, move onto the 3rd and 4th Pair as specified above.
You will hear the dial tone when you've got the correct pair but don't keep hold of the wires with your fingers. If someone calls, you'll get a shock of about 75 volts AC. That stings a bit and if you are up a pole might be enough to cause you to lose grip.
Once connected, you can use the phone as normal BUT incoming calls won't "Ring".
That's because the master socket in the house filters the ringing tone onto a different pin i.e. Pin 3 of your BT plug.
There again you'd only be interested in calling someone for help not receiving calls.
As for OPSEC.
The home owner (if present) may hear a ping or two as you play about and if they pick up the phone when you are talking, they will hear you and I'm pretty certain they will want to say something to you.
That's it except to repeat :
It is illegal to hook up directly to the phone lines outside a building even if it's your own.
All information is available on the Internet if you wish to research this further.
This article is for information purposes only
It is illegal to hook up directly to the phone lines outside a building even if it's your own.
All information is available on the Internet if you wish to research this further.
This article is for information purposes only
RE: Telephone systems - NorthernRaider - 11 August 2012
Excellent bit of historical information for research purposes ?
RE: Telephone systems - Hrusai - 11 August 2012
great article mate, very informative, cheers for this!
RE: Telephone systems - Tigs - 12 August 2012
wow! thanks great info
RE: Telephone systems - bigpaul - 12 August 2012
didnt Post Office(pre BT) engineers have a clip on field phone they used to use? probably changed everything since my day, i was a Post Office telephone operator back in the early 70's.
RE: Telephone systems - Hrusai - 12 August 2012
(12 August 2012, 09:12)bigpaul Wrote: didnt Post Office(pre BT) engineers have a clip on field phone they used to use? probably changed everything since my day, i was a Post Office telephone operator back in the early 70's.
ill ask my mum, shes the manager of a shop and post office! so she should know
(12 August 2012, 13:02)Hrusai Wrote: ill ask my mum, shes the manager of a shop and post office! so she should know
ok well she doesnt even know xD
probably not though
RE: Telephone systems - Paul - 12 August 2012
(12 August 2012, 09:12)bigpaul Wrote: didnt Post Office(pre BT) engineers have a clip on field phone they used to use? probably changed everything since my day, i was a Post Office telephone operator back in the early 70's.
Yes and surprisingly enough it was called a service or field test handset.
To buy a proper one now would cost over £100 as time, health and safety, electrical, all the CE bit, and Euro standard testing has done it's normal trick and increased the cost to ridiculous levels.
I used to install telecoms, mini exchanges, and key telephone systems. Our EX GPO guy had one. He could could do all sorts of creepy technical things with it. Very nice, very yellow, and VERY HEAVY.
I just made a couple of service phones out of a cheapy wall phones for me and my 'lad' with built in ringer capacitors, polarity and ring LED's, and various leads.
The GPO guy left shortly after that taking my new handset with him. Blinking nerve of it!
Remember though, all you need is the basics. Cheap little wall mounted one piece telephone and two small insulated crocodile clips.
K.I.S.S. rules!
RE: Telephone systems - Timelord - 12 August 2012
Telecoms operatives still use those handsets nowadays. Standard stuff. Tis one of my professions[/u]. I have a few knocking around my place;-) Well built bits of kit that last for ever and you can monitor calls without being apparent on the line.
A normal phone will not ring out upon receiving a call on the line (not an issue if you are just making a call) unless it has a master socket it is plugged into or it is in an extension socket with a 3 wire connection. The test phones all have capacitors built in that enable them to ring out on any 2 wire connection. TL.
RE: Telephone systems - 00111001 - 13 August 2012
Did a stint for BT and for NTL as an installer. See if you can find an old "Butt Phone" (that's what we called 'em) - they're the bright yellow or red ones. Then all you have to do is bust open the distro or mux unit doors and jack yourself into someone elses phone line. You can do it with a normal telephone with some jiggery pokery, but these phones are much better. Got caught a couple of times "borrowing" someones line when they picked up expecting to make a call only to hear me chatting to someone at control!
Be warned though, if you're playing with a mux unit you can get a bit of a shock. The quickest way to tell if a line was live into a property was to strip the wires and stick 'em in your gob. Little shock and the line is fine. I tried this at the distro hub, voltage much higher than I expected. 2 little burns on my tongue, and I spent the rest of the day dribbling
