The Hacker's Encyclopedia 1998

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