258 lines
12 KiB
Plaintext
258 lines
12 KiB
Plaintext
==Phrack Magazine==
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Volume Five, Issue Forty-Five, File 23 of 28
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****************************************************************************
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AN INTRODUCTION TO OCTELS
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AUTOMATIC SPEECH EXCHANGE NETWORK
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BY OPTIK NERVE
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(nerve@netaxs.com)
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The Automatic SPeech Exchange Network, or ASPEN for short, is a high
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performance voice processing system which interfaces and integrates with a
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variety of PBX and Central Office (CO) equipment. Interfaced systems require
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the caller to enter an extension, while integration provides a personal
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greeting automatically. Both of these provide the ability to return to the
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operator if necessary. ASPEN systems offer voice mail, Information Center
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Mail-Boxes (ICMB), Enhanced Call Processing (ECP), networking, and
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transaction processing. The Aspen, Branch, Branch XP, and VPC 100 hardware
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is only significantly different in their port and drive capacities. The
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following information is presented to introduce an overview of the hardware
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in an ASPEN system, and its function for it as a whole. This is not a
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"how-to" file and you will not find anything related to fraud in this
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article.
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SYSTEM COMPONENTS LIST
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-=-=-=-=-=-=-=-=-=-=-=-
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Each ASPEN system contains the main cardcage, the I/O cardcage, the drives,
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power supplies, and the system manager terminal. The system manager printer
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is optional. ASPEN hardware consists of:
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o CPU Board
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o File card
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o Line board
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o Telephone Interface Card (TIC)
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o Scanner board
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o Winchester drives
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o Power supplies
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o System manager terminal
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o System manager printer (optional)
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The cardcages of the system contain the following boards, each identifiable
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by a unique color coded tab indicating the slot into which the board fits.
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MAIN CARDCAGE
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o CPU (yellow)
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o File card (dark green)
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o Line boards (light green)
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INPUT/OUTPUT CARDCAGE
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o Scanner board (pink)
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o TICs (purple)
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SYSTEM COMPONENTS OVERVIEW
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-=-=-=-=-=-=-=-=-=-=-=-=-=-
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The following subsections present a functional description of the
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characteristics considered standard on ASPEN system hardware.
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CENTRAL PROCESSING UNIT
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~~~~~~~~~~~~~~~~~~~~~~~
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The CPU board contains a microprocessor with access to one megabyte of
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RAM. It is identical, in function, to a personal computers' CPU,
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executing instructions, and controlling serial I/O to the scanner board
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and system manager terminal.
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SYSTEM DATA BUSES
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~~~~~~~~~~~~~~~~~
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System communication between the boards uses three main buses: the control
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bus, the data bus, and the polling/status bus. The eight megahertz control bus
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works on a request/response procotol; for each 16 byte message sent by the
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CPU to a board, a 16 byte response must be sent back to the CPU. The data bus
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moves large amounts of data (20KB transfers) between the CPU, file card, and
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line boards at eight megahertz. All digitized speech to and from the line
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boards and file card travel on this bus. The polling/status control bus is
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used only between the scanner board and TICs. The scanner board polls each TIC
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port for an on-hook/off-hook status every ten milliseconds.
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FILE CARD
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~~~~~~~~~
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The file card controls the drives and is the primary system file manager.
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The file card controls the Winchester ST-506 interface. The file card also
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stores frequently used prompts of less than three seconds in a speech cache
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memory.
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LINE BOARD
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~~~~~~~~~~
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The line board contains microprocessors with access to 128KB of RAM. The
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line board has four channels, each matching a channel on a TIC. The Aspen may
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contain as many as six line boards, but this is limited to four, and even
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two on lower end Aspen models. Line boards perform several important
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functions including: encoding and decoding of digitized speech, tone
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detection, DTMF detection, silence detection, speed control, and DTMF tone
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generation. Speech is encoded at a rate of 25K samples per second using Delta
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modulation. Each of the four channels on the line board has a tone detection
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circuit, which detects dial, busy, reorder, and ringback tones generated by
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most PBXs and COs. The proprietary design limits talk-off during message
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playback. Talk-off may occur when the voice generates tones similar to DTMF
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tones. Silence detection recognizes spaces between words so that the voice
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message can be compressed for disk storage, optimizing disk space. The
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system also recognizes silence during message recording and prompts the user
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to continue. The line board controls message playback speed without
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affecting voice frequency pitch by controlling the amount of silence
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between words. Playback can be normal, slow, or fast. The line board is
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equipped with a tone generator used for dialing when ASPEN places an
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outcall or transfers a call.
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TELEPHONE INTERFACE CARDS
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~~~~~~~~~~~~~~~~~~~~~~~~~
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The Telephone Interface Cards (TICs) provide interfaces to either the
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Public Switched Telephone Network (PSTN) including CO, or to a PBX. In
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most installations, the TIC emulates a regular telephone to the PBX or the
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CO. Octel Communications has special TICs that emulate electronic digital
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sets in a Mitel PBX and ROLM PBX. The four channels on a TIC connect
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directly to the four channels on a line board. The TICs use transformers to
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provide electrical isolation to protect the line board and the network or PBX.
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The TICs communicate with the scanner board through the polling/status
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control bus located on the I/O backplane.
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SCANNER BOARD
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~~~~~~~~~~~~~
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The scanner board, as mentioned above, communicates with all TICs through
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the polling/status control bus. By continually polling all TIC channels, the
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scanner board detects new incoming calls and reports this change in status
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information to the CPU board though one of the four serial I/O ports. It also
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provides RS-232 data connection to the PBX when required, and the serial I/O
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port which interfaces the system managers terminal with the CPU. The scanner
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board includes a built in modem used to remotely access the system
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administration functions. The local system manager terminal and the modem
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circuit share the same serial I/O port, and the first connection has priority
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over the second. (ie: If the modem is connected, the local system manager
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terminal cannot access the system)
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SYSTEM MANAGER TERMINAL/PRINTER
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The system manager terminal is used to enter and change information within
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the system database. The system manager terminal is a Wyse 50 terminal
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used by ASPEN to report administrative information. The printer is an
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optional device used to produce a hard copy of output produced.
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DISK COMMUNICATOR
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~~~~~~~~~~~~~~~~~
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The Disk Communicator provides connections between the file card and the
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drives. If more than four drives are installed, a multiplexer (MUX)
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communicator board selects the four drives in the first cabinet and the
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four drives in the second cabinet.
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WINCHESTER DRIVES
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~~~~~~~~~~~~~~~~~
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These drives store system software, mailboxes, voice prompts, messages, and
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greetings. Octel Communications uses its own formatting technique and disk
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controllers. Standard drives are formatted for a capacity of 60, 90, or 190
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megabytes. The drives (0-1) contains all software and voice prompts needed to
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operate the system.
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POWER SUPPLY
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~~~~~~~~~~~~
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The ASPEN power supply is located in the center of the system housed in a
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single case, which actually contains two supplies. One supplies +5/-5 and
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+12/-12 volts to the boards, while the other provides +12 volts for the
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drive motors. There are no replaceable fuses in an ASPEN system. If the
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current draw or input voltage reaches a defined level, the power supply
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turns itself off automatically, necessitating a reset of a single circuit
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breaker.
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SPECIAL INTEGRATION DEVICES
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The Woobox and the PBX Integration Device (PID) provide integration to
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different PBXs. These devices stand alone and are peripheral to the ASPEN
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chassis. ASPEN integrates with the AT&T Systems 75 and 85 using an A/PID.
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THE CALL PROCESS
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-=-=-=-=-=-=-=-=-
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The following is a general description of a typical call through ASPEN and
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the boards involved in the process:
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o Subscriber dials the ASPEN pilot number, either directly or is
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forwarded to APSEN by the PBX.
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o A TIC senses ring voltage and raises a flag to indicate an
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incoming call.
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o The scanner board polls all TICs for change of status using the
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polling/status control bus and detects the raised flag.
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o The scanner board commands the TIC to answer the call (go off-hook)
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by sending a command on the polling/status control bus
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o The scanner board alerts the CPU board of an incoming call
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by sending port identification information over the serial
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I/O port.
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o The CPU commands the corresponding port on the line board to
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begin listening for DTMF tones, silence, or dial tone. The line
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board informs the CPU of call process through the control bus.
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o The CPU commands the file card to send digitized voice prompts,
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"Hello, this is ASPEN...", over the data bus to the proper
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port on the line board. The line board converts these prompts
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to analog and passes them to the TIC
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o The caller dials the desired destination number through DTMF.
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The line board interprets these and passes the information
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to the CPU.
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o The CPU instructs the file card to find the user record of the called
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party, check for the location of the personal greeting, retrieve the
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greeting, and pass it to the line board. The line board converts the
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greeting to analog and passes it to the TIC
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o After the greeting plays, the caller records a message. The line board
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digitizes speech and stores it in buffers of six seconds each (20KB)
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o Using the control bus, the CPU sets a data bus transfer between the line
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board and file card. The file card decides which drive has the most free
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space and where to wire this message. The six seconds of digitized speech
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is transferred from the line board to the file card. The file card then
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writes the six second segment to the disk. This process continues until
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the caller finishes the message.
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o The file card updates the user record of the called party by placing 11
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bytes in the mailbox. The 11 bytes define the message location on the
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disk, sender, time, priority, and length.
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o The caller terminates the call by pressing the one key
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o The line board informs the CPU through the control bus that the call has
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been terminated
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o The CPU commands the file card to send the good-bye prompt to the line
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board which converts it to analog and passes it to the TIC
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o The CPU commands the scanner board to disconnect that port
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o The scanner board commands the TIC to hang-up (go on-hook) through the
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polling/status control bus
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o The scanner board continues polling all TIC ports for change of status
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CONCLUSION
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-=-=-=-=-=-
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I hope this information provides you with a more solid background of
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how the ASPEN system functions. The basic aspects of this system can also
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apply to other similar PBX interfaces. Although the above information
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cannot really be used for anything illegal, I have provided it, for
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informational purposes, to those who "feed" on telco-bits as I do.
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Greets go out to: Ludichrist, Squarewave, the ID-Crew,
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#hack, and #phreak
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You can reach me at nerve@netaxs.com, but please use my following
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public key to encrypt all mail before sending it. Thank you...
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Version: 2.3
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