==)--- P TO PAUSE S TO STOP ---(==  The Phreaker's Guide to Loop Lines by Lefty Carlson & Landau Ltd _______________________________________ Revised: April 5, 1985 A loop is a wonderous device which the telephone company created as test numbers for telephone repairmen when testing equipment. By matching the tone of the equipment with the tone of the loop, repairmen can adjust and test the settings of their telephone equipment. A loop, basically, consists of two different telephone numbers. Let's use A and B as an example. Normally if you call A, you will hear a loud tone (this is a 1004 hz tone), and if you call B, the line will connect, and will be followed by silence. This is the format of a loop line. Now, if somebody calls A and someone else calls B--Viola!--A and B loop together, and one connection is made. Ma Bell did this so repairmen can communicate with each other without having to call their own repair ofnice. They can also use them to exchange programs, like for ANA or Ringback. Also, many CO's have a "Loop Assign}ent Center". If anyone has any information on these centers please tell me. Anyway, that is how a loop is constructed. From this information, anyone can find an actual loop line. Going back to the A and B example, Note: the tone side and the silent side can be either A or B. Don't be fooled if the phone company decides to scramble them around to be cute. As you now know, loops come in pairs of numbers. Usually, right after each other. For example: 817-972-1890 and 817-972-1891 Or, to save space, one loop line can be written as 817-972-1890/1 (according to the Landau Shorthand For Numbers. This is not always true. Sometimes, the pattern is in the tens or hundreds, and, occaisionally, the numbers are random. In cities, usually the phone company has set aside a phone number suffix that loops will be used for. Many different prefixes will correspond with that one suffix. In Arlington, Texas, a popular suffix for loops is 1893 and 1894, and a lot of prefixes match with them to make the number. For Example: 817-460-1893/4 817-461-1893/4 817-465-1893/4 817-467-1893/4 817-469-1893/4 ...are all loops... or a shorter way to write this is: 817-xxx-1893/4 xxx= 460, 461, 465, 467, 469 Note: You can mix-and-match a popular suffix with other prefixs in a city, and almost always find other loops or test numbers. Note: For Houston, the loop suffixes are 1499 and 1799. And for Detroit it's 9996 and 9997. When there are a large number of loops with the same prefix format, chances are that many loops will be inter-locked. Using the above example of Arlington loops again, (I will write the prefixes to save space) 460, 461, and 469 are interlocked loops. This means that only one side can be used at a given time. This is because they are all on the same circuit. To clarify, if 817-461-1893 is called, 817-460 and 469-1893 cannot be called because that circuit is being used. Essentialy, interlocked loops are all the same line, but there are a variety of telephone numbers to access the line. Also, if the operator is asked to break in on a busy loop line he/she will say that the circuit is overloaded, or something along those lines. This is because Ma Bell has taken the checking equipment off the line. However, there are still many rarely used loops which can be verfied and can have emergency calls taken on them. As you have found out, loops come in many types. Another type of loop is a filtered loop. These are loop lines that the tel co has put a filter on, so that normal human voices cannot be heard on either line. However, other frequencies may be heard. It all depends on what the tel co wants the loop to be used for. If a loop has gotten to be very popular with the local population or used frequently for conferences, etc. the tel co may filter the loop to stop the unwanted "traffic". Usually, the filter will be removed after a few months, though. The wise and knowledgeable phreaker can use loops in many ways. If there is a person he/she wants to talk to, but does not want to give them their home telephone number, then they can meet on a loop. Conferences can be set up on loops. Collect calls can be accepted on loops. If a loop is unmonitered, then it can be called free from a pay phone (this has many good uses if you think about it). Therefore, loops can be a powerful tool if used correctly, and not abused. They can make a good phreak's life a lot easier. I hope that this tutorial is of use to everyone who reads it, and was enjoyable. We, here at the Landau Ltd Mansion, enjoyed writing it. Look for more articles, files, and tutorials from myself, Lefty Carlson, and Landau Ltd in the future. PS: Look out for a part 2 of this series. Of which, I plan it to include as large a list of working loops as possible. I'm not exactly sure how to do it, but if anyone has any ideas please leave me mail. Remember: Comments, critisisms, critiques, or er criteria are always welcome! ---> The End <--- _______________________________________ R. 1985/LL  LIBRARY MENU #1 )