How Ma Bell Works                               by the Jolly Roger
In  this  article,  I  will first describe  the  termination,  
wiring,  and  terminal  hardware most commonly used in  the  Bell  
system, and I will include section on methods of using them. 
The   local   telephone   network   between   the    central  
office/exchange  and  the  telephone subscribers can  be  briefly  
described as follows: 
From  the  central office (or local exchange) of  a  certain  
prefix(es), underground area trunks go to each area that has that  
prefix  (Usually  more than one prefix per area.)  At  every  few  
streets or tract areas, the underground cables surface. They then  
go to the telephone pole (or back underground,  depending on  the  
area)  and  then  to the subsribers house (or in the case  of  an  
apartment building or mutliline business,  to a splitter or  dis- 
tribution box/panel).  
Now  that  we have the basics,  I'll try and go in-depth  on  the  
These  are sometimes inter-office trunks,  but usually in  a  
residential  area they are trunk lines that go to bridging  heads  
or  distribution  cases.  The cables are about 2-3  inches  thick  
(varies),  and  are  either  in  a metal  or  pvc-type  pipe  (or  
similiar).  Rarely (maybe not in some remote rural areas) are the  
cables  just 'alone' in the ground.   Instead they are usually in  
an  underground cement tunnel (resembles a small sewer or  storm- 
drain.)   The manholes are >heavy< and will say 'Bell system'  on  
them.  they can be opened with a 1/2 inch wide crowbar (Hookside)  
inserted  in the top rectangular hole.  There are ladder rungs to 
help you climb down.  You will see  the cable  pipes on the wall, 
with the blue and white striped one being  the inter-office trunk 
(at  least  in my  area).  The others  are local  lines,  and are 
usually marked or color  coded.  There is almost  always a posted 
color code  chart on the wall, not to mention  Telco manuals de- 
scribing the cables and terminals, so I need not get into detail. 
Also, there is usually  some kind  of  test equipment,  and often 
Bell test sets are  left  in there. 
The  innocent-looking  grayish-green boxes.   These  can  be  
either trunk bridges or bridging for residences.  The major trunk  
bridging  heads  are usually larger,  and they have the  'Western  
Electric' logo at the bottom,  whereas the normal bridging  heads  
(which  may  be different in some areas-depending on the  company  
you are served by.  GTE B.H.'s look slightly different.  Also, do  
not  be  fooled by sprinkler boxes!)  They can be found  in  just  
about every city. 
To open a bridging head: if it is locked (and you're feeling  
destructive),  put a hammer or crowbar (the same one you used  on  
the  manhole) in the slot above the top hinge of the right  door.   
Pull hard, and the door will rip off. Very effective! If it isn't 
locked (as usual),  take a 7/8 inch hex socket and with it,  turn 
the bolt  about 1/8 of a turn  to the  right  (you  should hear a 
spring release inside). Holding the bolt, turn the handle all the 
way to the left and pull out. 
To Check for a test-set (which are often left by Bell employees), 
go inside - First check  for a test-set  (which  are  often  left  
by  Bell  employees).   There should be a panel of terminals  and  
wires.   Push the panel back about an inch or so,  and rotate the  
top  latch  (round with a flat section)  downward.   Release  the  
panel  and it will fall all the way forward.  There is usually  a  
large  amount  of wire and extra terminals.   The  test-sets  are  
often hidden here,  so don't overlook it (Manuals,  as  well,  are  
sometimes placed in the head).   On the right door is a metal box  
of alligator clips.   Take a few (Compliments of Bell.).  On each  
door is a useful little round metal device. (Says 'insert gently'  
or'  clamp  gently - do not overtighten' etc..)  On the front  of  
the disc, you should find two terminals.  These are for your test  
set.   (If you dont have one, dont despair -I'll show you ways to  
make basic test sets later in this article). 
Hook the ring (-) wire to the 'r' terminal;  and the tip (+)  
wire  to the other.  (By the way,  an easy way to  determine  the  
correct polarity is with a 1.5v LED.   Tap it to the term.  pair,  
if  it  doesnt light,  switch the poles until it does.   When  it  
lights,find the longer of the two LED poles:  This one will be on  
the  tip wire (+).   Behind the disc is a coiled  up  cord.  This  
should have two alligator clips on it..  Its very useful, because  
you dont have to keep connecting and disconnecting the fone (test  
set) itself, and the clips work nicely. 
On  the  terminal  board,  there should be  about  10  screw  
terminals  per  side.   Follow the wires,  and you can see  which  
cable pairs are active.  Hook the clips to the terminal pair, and  
you're set!   Dial out if you want,  or just listen (If someone's  
on theline).  Later,  I'll show you a way to set up a true  'tap'  
that  will let the person dial out on his line and receive  calls  
as normal, and you can listen in the whole time.  More about this  
On  major  prefix-area bridging heads,  you can  see  'local  
loops' ,which are two cable pairs (cable pair = ring+tip,  a fone  
line)  that are directly connected to each other on the  terminal  
board.   These  'cheap  loops' as they are called,  do  not  work  
nearLy  as  well  as the existing ones set up  in  the  switching  
hardware  at the exchange office.   (Try scanning your  prefixes'  
00xx  to 99xx #'s.)  The tone sides will announce themselves with  
the 1008 hz loop tone,  and the hang side will give no  response.   
The  first  person  should dial the 'hang' side,  and  the  other  
person dial the tone side,  and the tone should stop if you  have  
got the right loop.) 
If  you want to find the number of the line that you're  on,  
you  can either try to decipher the 'bridging log' (or whatever),  
which is on the left door.  If that doesnt work,  you can use the  
     ANI # (Automatic Number ID) 
This  is a Telco test number that reports to you the  number  
that youre calling from (It's the same, choppy 'Bell bitch' voice  
that you get when you reach a disconnected #)  
For the   213 NPA - Dial 1223 
          408 NPA - Dial 760 
          914 NPA - Dial 990 
These  are  extremely useful when messing with any  kind  of line
terminals, house boxes, etc. 
Now that we have bridging heads wired, we can go on... (don't  
forget to close and latch the box after all... Wouldnt want GE  
and Telco people mad, now, would we?)  
     "CANS" - Telephone Distribution Boxes 

Basically, two types: 
1> Large, rectangular silver box at the end of each street. 
2> Black, round, or rectangular thing at every telephone pole. 
Type 1 -   This is the case that takes the underground cable from  
the  bridge and runs it to the telephone pole cable (The  lowest,  
largest  one  on the telephone pole.)  The box is always  on  the  
pole nearest the briging head, where the line comes up.  Look for  
the 'Call before you Dig - Underground cable' stickers.. 
The  case box is hinged,  so if you want to climb the  pole,  
you  can open it with no problems.   These usually have 2 rows of  
terminal sets.  
You  could try to impersonate a Telco technician and  report  
the  number as 'new active' (giving a fake name and fake  report,  
etc.)   I  dont recommend this,  and it  probably  won't  (almost  
positively won't) work,  but this is basically what Telco linemen  
Type  2 - This is the splitter box for the group of houses around  
the  pole  (Usually  4 or 5 houses).   Use it  like  I  mentioned  
before.   The terminals (8 or so) will be in 2 horizontal rows of  
sets.   The  extra  wires  that  are  just  'hanging  there'  are  
provisions for extra lines to residences (1 extra line per house,  
thats  why  the insane charge for line #3!)  If its the  box  for  
your  house  also,  have fun and swap lines with  your  neighbor! 
'Piggyback'  them  and  wreak havoc  on  the  neighborhood  (It's  
eavesdropping  time...)  Again,  I don't recommend this,  and its  
difficult to do it correctly.  Moving right along... 
Found  outside the buliding (most often on the  right  side,  
but not always...   Just follow the wire from the telephone pole)  
or  in the basement.   It has a terminal for all the lines in the  
building.   Use it just like any other termination box as before.  
Usually says 'Bell system' or similar.  Has up to 20 terminals on  
it (usually.) the middle ones are grounds (forget   these).   The  
wires come from the cable to one row (usually the left one), with 
the other row of terminals for the other row of terminals for the  
building  fone wire pairs.   The ring (-) wire is usually the top  
terminal if the set in the row (1 of 10 or more),  and the tip is  
in the clamp/screw below it.  This can be reversed, but the cable  
pair is always terminated one-on-top-of-each- other,  not on  the  
one  next  to  it.  (I'm  not sure why the other  one  is  there,  
probably as aprovision for extra lines) Don't use it  though,  it  
is usually to close to the other terminals, and in my experiences  
you get a noisy connection. 
Final note:  Almost every apartment, business, hotel, or anywhere  
there   is  more  than  2  lines  this  termination  lines   this  
termination method is used.  If you can master this type, you can  
be  in control of many things...   Look around in your area for a  
building  that  uses this type,  and practice hooking up  to  the  
line, etc. 
As  an  added  help,here is the basic  'standard'  color-code  for  
multiline terminals/wiring/etc... 
Single line:  Red = Ring 
            Green = Tip 
           Yellow = Ground * 
*  (Connected  to  the ringer coil  in  individual  and  bridged  
    ringer   phones (Bell only)  Usually  connected to the  green  
Ring (-) = Red 
           White/Red Stripe 
           White/Orange Stripe 
           Black/Yellow Stripe 
Tip (+) =  Green (Sometimes 
            yellow, see above.) 
           White/Green Stripe 
           White/Blue Stripe 
           Black/White Stripe 
Ground =   Black 
Small,  gray (can be either a rubber (Pacific Telephone) or  hard 
plastic  (AT & T) housing deal that connects the cable pair  from  
the  splitter box (See type 2,  above) on the pole to your  house  
wiring.  Only 2 (or 4, the 2 top terminals are hooked in parallel  
with the same line) terminals, and is very easy to use.  This can  
be  used to add more lines to your house or add an external  line  
outside the house. 
      TEST SETS 
Well,  now  you  can  consider  yourself a minor  expert  on  the  
terminals and wiring of the local telephone network.  Now you can  
apply  it  to whatever you want to do..  Here's another  helpful  
How  to  make  a Basic Test-Set and how to use it  to  dial  out,  
eavsdrop, or seriously tap and record line activity. 
These are  the  (usually) orange hand set fones  used  by  Telco  
technicians to test lines.   To make a very simple one,  take any  
Bell (or other,  but I recommend a good Bell fone like a princess  
or a trimline. gte flip fones work excllently, though..) fone and  
follow the instructions below. 
Note:    A 'black box' type fone mod will let you tap into  their  
line,  and with the box o,  it's as if you werent there. they can  
recieve  calls and dial out,  and you can be listening the  whole  
time! very useful.  With the box off, you have a normal fone test  
A  basic black box works well with good results.   Take the cover  
off  the fone to expose the network box (Bell type  fones  only).   
The  terminal should have a green wire going to it (orange or  
different  if  touch tone - doesnt matter,  its the same  thing).  
Disconnect the wire and connect it to one pole of an SPST switch.   
Connect  a  piece  of wire to the other pole of  the  switch  and  
connect it to the  terminal.   Now take a 10k hm 1/2 watt 10%  
resistor  and  put  it  between the   terminal  ad  the    
terminal,  which  should have a blue and a white wire going to it  
(different for touch tone).  It should look like this: 
-----Blue wire---------- 
----White wire-----! 
              10k Resistor 
--Green wire--     !---- 
              !    ! 
What  this  does in effect is keep the hookswitch  /  dial  pulse  
switch (F to RR loop) open while holding the line high with  the  
resistor.   This gives the same voltage effect as if the fone was  
'on-hook',  while  the 10k ohms holds the voltage right above the  
'off hook' threshold (around 22 volts or so, as compared to 15-17   
or normal off hook 48 volts for normal 'on-hook'), giving 
Test Set Version 2.
Another  design is similar to the 'type 1' test set (above),  
but has some added features:
From >----------------Tip----------------------Ring-----all< audible line activity,  and the people (the 'eavesdropees')  
can use their fone as normal. 
Note that test sets #1 and #2 have true 'black boxes', and can be  
used for free calls (see an article about black boxes). 

Test Set Version 3 

To do test set 3: 
Using a trimline (or similar) phone, remove the base and cut  
all  of  the wire leads off except for the red (ring -)  and  the  
green  (tip +).   Solder alligator clips to the  lug.   The  wire  
itself  is  'tinsel' wrapped in rayon,  and doesnt solder  well.   
Inside  the one handset,  remove the light socket (if it has one)  
and install a small slide or  toggle switch (Radio Shack's micro-  
miniature  spst works well).   Locate the connection of the  ring  
and the tip wires on the pc board near where the jack is  located  
at the bottom of the handset.  (The wires are sometimes black or  
brow instead of red and green,  respectively).   Cut the foil and  
run 2 pieces of wire to your switch.  In parallel with the switch  
add  a .25 uf 200 VDC capacitor (mylar,  silvered mica,  ceramic,  
not  an electrolytic).  When the switch is  closed,  the  handset  
functions normally.   With the switch in the other position,  you  
can listen without being heard. 
Note:  To  reduce the noise involved in connecting the clips to a  
line,  add  a  switch selectable 1000 ohm 1/2  watt  resistor  in  
series with the tip wire. Flip it in circuit when connecting, and  
once on the line, flip it off again. (or just use the 'line disc-  
onect'  type  switch as in the type 2 test  set  (above)).   Also  
avoid   touching the alligator clips to any metal parts or  other  
terminals,  for  i causes static on the line and raises  poeple's  
If you would like to record any activity,  use test set 1 or  
2  above  (for unattended recording of >all< line  activity),  or  
just  any test set if you are going to be there to  monitor  when  
they are dialing, talking, etc.  
Place  a  telephone pickup coil (I recommend the Becoton  T-5  TP  
coil  or equivalent) onto the test set,  and put the TP plug into  
the mic.  jack of any standard tape recorder.  Hit play, rec, and  
pause.   Alternate  pause when you want to record (I  dont  think  
anyone should have any difficulty with this at all...) 
Well,  if  you  still can't make a test set or you dont have  the  
parts, there's still hope.  Alternate methods:          
1>  Find  a  bell test set in a manhole or a  bridging  head  and  
'Borrow it indefinately... 
2>  Test sets can  be  purchased from: 
    5 Apollo Road 
    Box 368 
    Plymouth Meeting PA., 19462 
Ask for catalog #28 
They  are usually $300 - $600, and are supposed to have  MF  
dialing  capability as well as TT dialing.  They are also of much  
higher quality than the standard bell test sets. 
If you would like to learn more about the subjects covered here,  
I suggest: 
1>  Follow Bell trucks and linemen or technicians and ask  subtle  
    questions. also try 611 (repair service) and ask questions.. 
2> Explore your area for any Bell hardware,  and experiment  with  
   it.  Don't try something if you are not sure what youre doing,  
   because you wouldnt want to cause problems, would you?