419 lines
18 KiB
Plaintext
419 lines
18 KiB
Plaintext
==Phrack Inc.==
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Volume One, Issue Eight, Phile #4 of 9
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The Integrated Services Digital Network
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---==> By Dr. Doom <==---
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ISDN or Integrated Services Digital Network has been talked about off and on
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by AT&T and until now has just been a demented AT&T fantasy, but it is to soon
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become a reality. This phile is the second I have written on the subject and
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is a cumulation of information from three basic sources :
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<1> The ISDN AT&T Technical Journal
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<2> An interview with an AT&T Long Distance Operations Center Supervisor who
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will be referred to as Mr. R.
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<3> and some general ISDN articles from Southwestern Bell Newsletters.
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ISDN Definition
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===============
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CCITT Definition : An end to end digital network that supports a wide range of
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services accessed by a set of standard multipurpose user-network interfaces.
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ISDN will allow for incredible new services that will drastically change the
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telecommunications industry and everyone's lives. For example, one new service
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ISDN will bring about is calling party identification. This will allow
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businesses and individuals who subscribe to that service to know exactly what
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number you are calling from before they even decide whether or not to answer
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the phone.
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In the case of dialups like MCI, the originating # will be stored in a computer
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along with whatever code and number that person dialed which would greatly
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hinder abuse of codes from a home phone.
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This is just the tip of the iceberg as far as ISDN is concerned. This phile
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will analyze and describe how The Integrated Services Digital Network will
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operate when it is implemented.
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Out of Band Signalling
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======================
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Essential to a network capable of providing such enhanced services as calling
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party identification is out-of-band signalling. Until the late 70's, when AT&T
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introduced the 4ESS toll switch and CCIS into the national network, switches
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had communicated with each other over the same channels in which our voice or
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data was transmitted (in-band). During this time, all signalling between
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switches had to be limited to a type that could be accommodated in the 'voice'
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channel thus making it impossible to offer any advanced services.
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The development of the separate Common Channel Interoffice Signaling (CCIS)
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network allowed for more freedom and flexibility and thus came about the AT&T
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Calling Card service.
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ISDN brings an interface from the network to the subscriber's equipment. This
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is a completely digital interface subdivided into two types of channels :
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The 'D' Channels are those used for sending signalling and control information
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across the interface. The 'B' Channels are those used only for customer
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information which can be in the form of voice, data, or video.
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The 'D' Channel hence manages the information or 'B' Channels making the
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signalling 'out-of-band' and not 'in-band' as it is now. This approach allows
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for two distinct benefits :
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<1> All the capacity in the information bearing channels is available for
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customer use.
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<2> The 'D' Signaling channel allows for distributed processing across the ISDN
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Network.
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ISDN Interfaces
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---------------
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The CCITT has defined two major interfaces that will be used in conjunction
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with the 'D' and 'B' channels :
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The Basic Rate Interface (BRI) consists of one D Channel and two B Channels.
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This interface is used for locations where information transport is relatively
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small like a residence.
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The Primary Rate Interface (PRI) consists of one 'D' Channel and 23 'B'
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Channels. It is used for large capacity vehicles such as PBX's.
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Notice that there are 2 DIFFERENT 'B' Channels in the Basic Rate Interface.
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This allows TWO different types of data to be sent over the same connection at
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the same time. For example, you could be ULing files to a board on Channel 1
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while talking to the SYSOP on Channel 2.
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So, if both you and a board both have a BRI ISDN Interface, next time the SYSOP
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says 'Go Voice', you simply pick up the handset, switch it to channel 2, and
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start talking...
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These multiple channels are also the foundation for the widespread use of Video
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Phones. Just like you were sending data over channel 1, and talking voice on
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channel 2, you can be sending video over channel 1 (allowing the party's to see
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each other) and talking on channel 2.
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ISDN Devices
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============
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AT&T Technologies, Advanced Micro Devices, and Intel are all in the process
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of designing equipment that will be compatible with ISDN. So far, the two main
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designs talked about through SWB and AT&T are :
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<1> The Voice/Data Terminal This will look like any regular computer terminal
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with the exception that it has a handset on the side of the terminal and a
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couple of switches that will allow you to decide which channel is for DATA
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and which channel is for VOICE. This will also (of course), allow two
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customers with a V/D Terminal to be exchanging DATA over one channel while
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talking voice over the other one.
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<2> The Video Phone
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This is where (yes) Big Brother is arriving... The Video Phone will work
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pretty much just like it does in Science Fiction movies like 'Aliens' or
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whatever. If two ISDN customers have video phones, they can talk and see
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each other or whatever they want to show each other (HAHA) at the same time.
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Video Phones obviously open up new frontiers for those with entrepreneurial
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instincts. You can bet there will be some interesting Video Phone Sex lines
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around... Then, you can have things like 'Dial a Movie...Please enter (1) to
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view Rambo'..etc... The list goes on. This also leads to a whole new world
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of problems for the telephone company like 'Obscene Video Calls'. This is
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again where Calling ID becomes important.
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Each of these units, and others that will work with ISDN will have some sort of
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a special viewing screen that will contain the necessary information about
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incoming calls which includes the originating number and can include such
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things as :
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<1> The name of the owner of that #
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<2> The city and state
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<3> The whole address for that #
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AT&T ISDN Building Blocks
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=========================
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AT&T has designated certain 'building blocks' that will eventually be laid in
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place across the entire country to form ISDN.
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<1> AT&T Communications Service Node
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------------------------------------
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The service node is the customer's gateway to the AT&T Communications nodal
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family of services, including MEGACOM, MEGACOM 800, and Acunet. The first
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service node went into service in 1985 in Philadelphia, PA.
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<2> Integrated Access
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---------------------
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This allows customers to integrate switched and private line services over a
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single DS-1 link to the Service Node.
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<3> Out-of-Band Signaling
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-------------------------
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Discussed earlier.
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<4> CCS7
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--------
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The CCS7 Common Channel Signaling Network will soon replace CCIS as an
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out-of-band signalling between AT&T Network Communications Facilities. Because
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of its longer message format and layered structure, the CCS7 will support the
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new features.
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<5> Digital Backbone Network
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----------------------------
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This nationwide AT&T Network includes extensive lightwave and digital radio
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routes. By the end of 1988, these Digital Lightwave routes will extend to
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Europe with the TAT-8 lightwave system, and across the Pacific with
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HAW-4/TPC-3.
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<6> Intelligent Software Controlled
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AT&T Communications Network
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-----------------------------------
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This brings about more advanced software related services listed in #1.
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AT&T ISDN Operations
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====================
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Access Transport
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----------------
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Your DS-1 signal is transported from your ISDN equipment to an AT&T
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Communications Service Node somewhere.
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Your line gets to AT&T by tariff from the local exchange carrier (i.e...
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Southwestern Bell, GTE, or whomever happens to own your local switch...) or
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AT&T. The direct link to the AT&T Service Node bypasses your local switching.
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AT&T Service Node
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-----------------
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Your local AT&T Service Node is a service office that acts as a gateway to
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all the new AT&T Nodal ISDN services. This service node is typically composed
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of :
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<1> A Refinished 4ESS Switch
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<2> CNI Ring (Common Net.-Interface)
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<3> Digital Access and Cross Connect System (DACS)
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Here is a diagram of how a customer location either goes to a local switch or
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AT&T's node :
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Key
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CL = Customer Location
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= = DS-1 Line
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! = DS-1 Line
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> = Exiting out to AT&T Network
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--------
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- -
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**** - Bell -
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*CL*=======- 5ESS -
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**** - -
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--------
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!
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!
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!
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!
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**** !
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*CL* --------!--------
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****===========4ESS=====>
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- 4ESS=
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**** - ! ! !
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*CL*======DACS=! ! CNI==>
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**** -DACS ! CNI
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-DACS= !
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- ! 1PSS====>
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- !=1PSS
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-
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-----------------
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AT&T Service
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Node
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The above diagram shows first how an AT&T Customer with ISDN can either
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continue service with his local telephone co. or go with a direct link to the
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AT&T Service Mode. All lines going to an AT&T Service Node whether through
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Bell or a direct link terminate on either the 4ESS or the DACS.
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When a line terminates on a DACS it serves as an Integrated Access
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Distributor and sends the call to the 1PSS (Packet Switch) for Acunet Packet
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Service or to the 4ESS and then eventually out to the AT&T Network.
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The AT&T Internodal Network
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---------------------------
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In the internodal network facility, AT&T is in the process of deploying both
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digital lightwave and digital radio systems.
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Lightguide Systems :
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In areas where growth is low, the FT3C and FTX180 Single mode terrestrial
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lightguide systems will be used between nodes.
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On high growth routes AT&T will install fiber pairs at line rates of 1.7Gb/s
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with 20 mile repeater spacings.
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Digital Radio :
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In the digital radio area, 4Gb/s systems such as the TD-90 and the TD-180
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provide a vehicle for rapid expansion of digital connectivity.
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ISDN and Digital Switches
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=========================
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AT&T has redesigned the 5E Switching Modules in such a way that they are
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fully compatible with ISDN, but many of the existing 5E's and other switches
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were manufactured without ISDN capability. To meet this need, AT&T has
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produced ISDN interfaces that modularly connect to the system. Here is a
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diagram of a 5ESS Switching Module with interfaces :
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Key
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$ = ISDN V/D Terminal or Video Phone
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% = Standard Telephone
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= = Digital Line
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< = In-Band Line
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ISLU = Integrated Services Line Unit
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PSIU = Packet Switch Interface Unit
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--------------------------
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- 5ESS -
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- Switching -
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- Module -
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- -
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------------=----=--------
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- = = -
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$====-----======== = -
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- - = -
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$====- - --------=--- -
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-ISLU- - - -
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%<<<<- ===== PSIU - -
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- - - - -
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$====--------------------------
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The two new hardware additions are :
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<1> Integrated Services Line Unit and
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<2> The Packet Switch Interface Unit
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These units allow a LOCAL 5ESS (or other digital) Switch to serve both ISDN
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and non-ISDN customers. These interfaces are integrated into a switching module
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in a way that will allow ISDN customers to maintain all their previous Bell
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services like Local Calling. Notice also that all lines, whether ISDN or not,
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terminate on the ISLU.
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Calling Party Identification
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============================
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Discussed briefly in the preface of this phile, the ISDN enhanced Calling
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Party Identification service offered by AT&T ISDN will be into service along
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with the ISDN.
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This quote out of the AT&T ISDN Technical reference should give you a good
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idea of the impact ISDN will have on hacking and phreaking :
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'One example of an enhanced service which has already been included in the
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ISDN signaling protocol and will have a fundamental impact on day to day
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telecommunications is the provisions of calling party identification.
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Calling party ID will help us decide whether or not to answer incoming calls
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and will minimize instances of nuisance calls and COMPUTER FRAUD via
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telephone.'
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Mr. R, our AT&T Supervisor has been attending ISDN Conferences that include
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representatives from all the major LD Companies (AT&T, MCI, GTE, LDS, etc..),
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the Regional Bells, and other concerned parties. He said quote 'One of the
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controlling factors behind The Integrated Services Digital Network is the
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simple fact that AT&T, MCI, and other long distance companies are losing
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MILLIONS to Phone Phraud.' Once ISDN is realized, so will network wide Calling
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Party Identification.
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Again, our friend Mr. R will enlighten us on the subject of ISDN Calling
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Party ID and a simple explanation of how it will work :
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'Right now, when you pick up the phone in your home, Port Isabel South
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Western Bell knows that you did. Then, when you dial a number, they know
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what number you dialed. So they send that information along to us (the AT&T
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Toll Switch). We then send that along through the network to the person you
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are calling.'
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Of course, there is one transaction between AT&T and a Bell Office at the end
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that he left off, but if the person or computer you are calling has ISDN
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Calling Party ID service, your originating # will be sent along the DS-1 Line
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Interface from Bell to his equipment and show up on his screen after traveling
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through the network like Mr. R described.
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This is rather simple when you think about it and is one example of how a once
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shattered network is working together.
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Some Sample CP ID Uses
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----------------------
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This can be used by large telephone ordering companies to instantly display a
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record of that persons credit, previous orders, etc... before the call is even
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answered on the attendant's terminal.
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When someone logs onto a computer, the originating # is listed on the user log
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along with the account name, etc... so that if there is an unauthorized login,
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they can contact the authorities to do whatever or monitor that number until
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they get enough evidence to prosecute. The same thing holds true with LD
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Dialups. They will record the originating number along with the code and bill
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making MCI use rather dangerous.
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SWB ISDN News
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=============
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The following article was extracted from The Southwestern Bell Texas
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Publication of Telephone Times and is entitled 'User Forum simplifies ISDN' :
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" Houston---Houston Marketing employees played show and tell with two customers
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and all three groups are better off for it.
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Marketing Representatives, with support from Bell Comm. Research, Illinois
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Bell, AT&T, and McDonald's Corp. met with Shell and Tenneco to discuss ISDN.
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'ISDN is an evolving technology' said Bob Campbell, division manager
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marketing business sales. 'It's still in the developmental stage. These User
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Forums will give customers input on how it's deployed and what it will look
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like.'
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ISDN is an all digital network that transmits voice and data messages
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simultaneously over a single telephone line.
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'The User Forums allow customers to share information on specific problems
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concerning implementation, training, customer premise equipment and
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applications,' Campbell said.
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Linda Hobson, manager marketing administrative and coordinator of the event,
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said not only will User Forums be standard practice in Houston, but probably
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will become the national standard.
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'We're doing it quarterly here, but as more people become interested, we may
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meet more often,' Hobson said.
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Shell and Tenneco, who have signed letters of intent to purchase ISDN, were
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specifically interested in such topics as trial status (SWBT's ISDN trials will
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begin soon in St. Louis and Texas), available features, power requirements, and
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future enhancements.
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'In the past, we bought the available enhancements, then sold them to the
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customer,' said Hobson. 'That's changing. We have to find out what the
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customer wants, then deliver the service that meets the specific needs'"
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That concludes the nice little article which by the way, contained some
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interesting little tidbits of information.
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Conclusion
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==========
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ISDN is a VERY complicated plan that will drastically change the
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telecommunications scene in this country and abroad. Although AT&T has boasted
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in it's Technical Journals of being able to have its ISDN Capable Network
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completed by Early 1987, this date seems to keep getting postponed back
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according to our friend Mr. R (The AT&T Supervisor) and he is shooting for
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large scale ISDN no earlier that late 1988 or 1989. Whenever ISDN does become
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reality, people will probably just put out files with lists of computers that
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subscribe to ISDN Calling Party Identification, and tell people not to call
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them from their home.
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I hope you have enjoyed reading this phile on ISDN, I will be on the outlook
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for more information on it.
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If you don't already have the # and New User Passwords to Metromedia BBS, send
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me (Dr. Doom) mail on any of the boards I am on.
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