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180 lines
8.6 KiB
Text
180 lines
8.6 KiB
Text
==Phrack Inc.==
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Volume Two, Issue 12, Phile #8 of 11
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BUSY LINE VERIFICATION PART II
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WRITTEN BY PHANTOM PHREAKER
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This file is meant to be an addition to the first file that was included
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in Phrack Inc. Issue XI. It is assumed that the reader has read and understood
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the previous file. Most of this information will be taken from Bell System
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Publications so you don't have to worry about it being incorrect.
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First off, I'd like to correct a minor error included in the first file. I
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use the format 'KP+0XX+PRE+SUFF+ST' to show the MF routing that is used. This
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is not correct AT&T syntax though, the correct format is KP+0XX+NXX+XXXX+ST.
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This is minor detail, but some people are very picky.
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The Verification Network
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------------------------
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In a TSPS office, a verification circuit is associated with a 4-wire
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OutGoing Trunk (OGT) and a 3-way/4-wire bridging repeater arrangement. This is
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the circuit that does the speech scrambling. The speech and other tones (like
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busy and re-order) are frequency shifted, but are still recognizable by a TSPS
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operator.
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TSPS verification trunks are connected via dedicated lines to incoming
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verification trunks in a toll office. The toll office provides either a link
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to an outgoing trunk and dedicated facilities to another toll office, or an
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outgoing toll connecting trunk and dedicated facilities to an incoming
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verification trunk in a local office. Each toll office has ways to check the
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security of verification trunks. In electronic toll offices (ESS offices), two
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independent office data translations provide security of the trunk. Electro-
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mechanical toll offices (Such as a CrossBar Tandem (XBT)) use an electrical
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cross-office check signal or a segregated switching train to control trunk
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connections. Verification trunks relay supervisory signals (such as answering
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supervision) to TSPS from the line being verified. Also, if verification
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trunks are busy, the TSPS operator will receive a re-order.
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The functions of the VFY key
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----------------------------
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When the operator presses the VFY key, several checks are made upon the
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number that has been entered. These are:
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A Check to see if the line is within the verification network accessible
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by that particular TSPS. If the line is not, the VFY key will flash.
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A check to see if the owner of the line wishes BLV to be possible or not.
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If the line is something like a police emergency line, then the VFY key will
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flash, similar to the first check.
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Important TSPS keys
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-------------------
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When the VFY lamp lights steady (doesn't flash), indicating the process is
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acceptable, the operator puts the calling customer on hold and accesses an
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idle loop on the operator position. The ACS (Access) lamp lights steady if a
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verification trunk is available at that time. Then, the operator presses the
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ST key which sends out the complete number to be verified, in MF. The
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verification circuit activates, and the operator listens for scrambled speech
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and also watches the CLD (Called) lamp on her console. The CLD lamp is lighted
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when the operator loop was accessed, and will remain lit if the line being
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verified is on-hook. The operator has two ways of seeing if the line is in
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use, by listening, and by watching the CLD lamp. If the CLD lamp light goes
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out, then the line is off-hook.
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If a successful BLV/EMER INT is performed, the operator presses the REC
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MSG MSG (Record Message) key, which completes the verification. If the EMER
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INT lamp is lit, the charges for the interrupt and the verification are
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automatically billed. If the VFY key is pressed twice, it indicates the
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verification should not be billed. This could be due to a customer error or a
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customer disconnect.
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Charging capabilities
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---------------------
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A customer can pay for a BLV/EMER INT in several ways. They can have the
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charges put on their phone bill, if they are calling from their home, they can
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bill the charges to an AT&T Calling Card, or pay directly from a coinphone.
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Details of the BLV/EMER INT function are recorded on AMA tape, which is later
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processed at the RAO (Revenue Accounting Office).
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The classes of charge are as follows: STATION PAID, which means exactly
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what it says, STATION SPECIAL CALLING, in cases where billing is handled by a
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Calling Card or third number billing, and NO AMA, in unusual billing cases.
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Also, for BLV/EMER INT calls that originate from a hotel, TSPS can send
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charges to HOBIS (Hotel Billing Information System), HOBIC (Hotel Billing
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Information Center), or a TTY at the hotel.
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AMA records for BLV/EMER INT are recorded in basically the same format
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that normal calls are recorded. The only difference is that a numeric data
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group is added. The leftmost digit in the data group is a 1 if only a BLV was
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done, but it is a 2 if both a BLV and an EMER INT were done. In case of an
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aborted BLV, the billing record is marked 'No charge'.
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Inward Operator differences
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---------------------------
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When an Inward operator does BLV/EMER INT, the class of charge is always
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NO AMA, because billing is handled at the local TSPS site. Inwards also do not
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use the REC MSG key when a TSPS would, they use the VFY key in it's place.
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The Speech scrambling technique
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-------------------------------
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The speech scrambling technique that exists to keep the customers privacy
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intact is located in the TSPS console, and not in the verification trunks. The
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scrambling technique can only be deactivated by an operator pressing the EMER
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INT key, or a craftsperson using the console in a special mode. When the
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scrambler is deactivated by an operator doing an EMER INT, the customer hears
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an alerting tone (as mentioned in the first BLV file) made up of a 440Hz tone.
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This tone is initially played for two seconds, and then once every ten seconds
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afterwards until the operator presses her Position Release (POS RLS) key.
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Operator trouble reporting
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--------------------------
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When operators have trouble in handling a call, they can enter trouble
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reports that are technically called 'Operator keyed trouble reports'. These
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cause messages to be printed on the maintenance TTY and on the trouble report
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TTY channel. There are different trouble codes for different things, such as
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trouble with the speech scrambler, trouble in the verification network, or
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trouble in collecting charges from a customer.
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In my area there are 20 such TSPS trouble codes. These are done in MF.
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They are entered with the KP TRBL (Key Pulse Trouble) key followed by a two
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digit trouble code followed by an ST. A trouble code for beeper trouble could
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be entered as KP TRBL+62+ST, and speech scrambler trouble could be KP
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TRBL+89+ST. Some of the other reasons for trouble codes are: Crosstalk, No
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ring, Noisy, can't hear, improper supervision toward the called and calling
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parties, cutoff, positions crossed, coin collecting trouble, third re-order,
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distant operator no answer, echo, data transmission, no answer supervision, ST
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key lit for more than 4 seconds, and others for person-to-person and
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station-to-station completed collect calls.
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Maintenance and traffic measurements
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------------------------------------
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These reports can be output from a maintenance or engineering and service
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data TTY, daily or hourly. Each daily report contains data for the previous
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day. Some traffic counts are as follows:
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Total Verification attempts, VFY key depressions, VFY key depressions when
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the requested number is out of TSPS range, VFY key depressions in which the
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requested number wasn't verifiable, BLV trunk seizures which pass an
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operational test, and EMER INT attempts. Other traffic counts include the
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measurements for usage of BLV trunks, the amount of time BLV trunks were
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unavailable, and the number of times BLV trunks were seized.
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I hope this file has helped people further understand how the BLV system
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works. If you haven't read part I, get a copy of Phrack Inc. Issue XI and read
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file #10.
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As said earlier, most of this information comes directly from Bell System
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Publications and so it should be viewed as correct. However, if you do find
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any errors then please try to let me know about them so they can be corrected.
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Suggested reading
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-----------------
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TSPS Part I: The console-Written by The Marauder, LOD/H Technical Journal
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Issue No. 1, file #4
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Busy Line Verification-Phrack Issue XI, file #10
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Busy Verification Conference Circuit-Written by 414 Wizard
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Verification-TAP issue 88, Written by Fred Steinbeck
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Acknowledgements
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----------------
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Bell System Technical Journal, Vol. 59, No 8.
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Bell Labs RECORD periodical
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And the following people for contributing information in some form:
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Mark Tabas, Doom Prophet, The Marauder
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