Volume I: Loop Arounds


                                   by

                            ThE pHoNeY pHrEaK

                   (Special Thanks to: The Jabberwock)


What is a loop around?  Well, I'll tell ya!  Loop arounds (also called cheap loops or test loops) are used by the telco for legitimate testing.  Mostly used by linemen or repairmen while they are in the manholes.  While in there, they have to way to communicate with other people since they don't have a phone to use.  They all have butt-sets that are used to tap into a block but no one number they can use to receive calls.  But since they have those butt-sets, this is how they make their call.  At a pre-determined time, the lineman will call one number while the other lineman or telco will call another number.  When this happens, they get connected.  The lines they use are very bad but nevertheless, it does its job.  However, some lines are very good!
Think of this as two lines floating around in the telco.  When one person dials one side and another person dial the other side...they get connected!  They permit two-way transmissions without far-end assistance.


                                   telco
    phone numbers             ----------------
                             |                |
        9917 --------------------------       |
                                        \     |
                                        /     |
        9918 --------------------------       |
                          |                |
                              ----------------



You're now thinking, "Big Deal!  Why do I need to know this?"  Well, weren't you ever hesitant to leave a number with someone?  Or how about using one side of the loop to accept collect calls?  Or maybe setting up a fake account and need some sort of call back number.  Or how 'bout getting an unsupervised loop.  This is when one side of the loop isn't charged.  This means that a person can call one side (a local call) and the other person would dial the unsup side.  You and your friend could talk for hours since it is only costing you for a local call (Most of these loops do not give answer supervision so it will be a free call.  These calls go usually undetected but remember, they can trace it.  And if you go through another carrier such as Sprint or AT&T, they can trace it too since they know what the loop numbers are in most metro areas).
Betcha got your interest now!  Well, here's how to find a loop.  There are usually one in every prefix (NXX).  You should search for them at night since linemen do use them during the day.  The numbers are found in either the 00XX side of the NXX or the 99XX side.  You should have a friend to help you since this can take a very long time.  I was lucky enough to find some on my first day of searching for this.
When you come across a loop, there will be one of two things you will hear.  Either a somewhat, loud steady tone or dead air.  One set of loops will be found in only one
prefix.  So don't go looking for one side of the loop in the 657 prefix and the ending loop in the 529 prefix.  If you are, stop reading and erase this file 'cuz you are too stupid to continue!
You may come across some numbers that will beep and click at various intervals.  These are also test numbers used by the telco.  They are synchronous type, nonsync type, 101-type, 102-type, etc tests.  The loop around test lines are 106-type tests.
Loops are for two people only but you might come across some that has conference calling capabilities (I have never got any line like this.  If this is true, I would like to get those numbers).  If it is a two person loop, the next caller will be qued in when the first caller hangs up.
Here is a few loops I found in my area:

498-1118/1119
735-1118/1119
529-9900/9906
352-9900/9906
455-9907/9908
836-9907/9908
283-9977/9979
986-9977/9979

As you can see, most of the numbers I found were located in the 99XX area in the prefix. There might be a few in the 00XX but I haven't come across any yet.  If you can get your hands on a Telephone Cross Directory (a backwards telephone book), it could save you numerous calls since you'll know if a resident or business has that number.  Usually payphones use the 99XX numbers (helps operators know if the person at that phone is calling from a payphone).
One person dials the tone side which is the lower number and waits.  The other person dials the higher number.  The high pitch tone goes away and then the lines get connected. Viola!  You can now talk to each other.  Try having another friend call one side of the loop to see if it has conference capabilities or having him call from an outer state or lata area to see if it is billing him.

Next up...Volume II - Wats Extenders & Volume III - Phreaky Phax