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REVIEW: "Telephone Switching Systems", Richard A. Thompson

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  • Rob Slade, doting grandpa of Ryan and Tr
    BKTLSWSY.RVW 20010126 Telephone Switching Systems , Richard A. Thompson, 2000, 1-58053-088-5, U$125.00 %A Richard A. Thompson rat@tele.pitt.edu %C 685
    Message 1 of 1 , Mar 5, 2001
      BKTLSWSY.RVW 20010126

      "Telephone Switching Systems", Richard A. Thompson, 2000,
      1-58053-088-5, U$125.00
      %A Richard A. Thompson rat@...
      %C 685 Canton St., Norwood, MA 02062
      %D 2000
      %G 1-58053-088-5
      %I Artech House/Horizon
      %O U$125.00 617-769-9750 fax: 617-769-6334 artech@...
      %P 859 p.
      %T "Telephone Switching Systems"

      It is a little disturbing to have the author of a book state that it
      should be accessible to any dedicated reader with some background in
      either electrical engineering or computer science, and then have him
      go on to assert that he assumes everyone knows about asynchronous and
      synchronous digital hierarchies (ADH and SDH). (This sounds worse
      than it is: readers with only a moderate familiarity with telephony
      will recognize the "T," "DS," and "OC" multiplexing numbers.)
      Nevertheless, as early as the preface the text demonstrates a humanity
      and readability that is very promising, attractive, and,
      unfortunately, unusual in technical writing.

      Chapter one starts by defining terms and concepts, beginning with the
      basics of communication, touching on networks, and finishing up with
      fundamental telephony operations. The material is clear and
      comprehensive. The background provided in chapter two starts with a
      business oriented history and moves to a discussion of switching
      architectures. While there are forward references to details of the
      switches mentioned, readers without telephony experience may fail to
      grasp some points. The line side of the system, from the telco switch
      to the handset, is covered in chapter three, with additional practical
      and personal content. The concepts involved in engineering trunks,
      the potentially long distance connections between switches, is dealt
      with in chapter four. Chapter five reviews the basics of traffic

      Chapter six looks at the Step architecture and the Strowger switch.
      However, the lack of a basic explanation of the switch operation is a
      serious limitation. The many detailed examples of special cases and
      exceptions are of restricted value when the primary operation is
      missing. Switch fabric is examined in chapter seven. Packet
      switching is included in the analysis, which is interesting since
      packet switching itself hasn't been discussed yet. Then back to a
      specific switch, Crossbar, in chapter eight, with a better, though
      still not complete, review of the physical operation. This chapter
      also compares Step against Crossbar in terms of maintenance. Chapter
      nine deals with toll points, billing, number plans, and other related

      Enterprise switching, in chapter ten, looks at the functions, history,
      and business aspects of PBXs (Private Branch eXchanges) but doesn't
      provide much information on the "how" of what happens.

      Chapter eleven goes back to specific switches, in this case the
      computer controlled #1 ESS. Thompson states that the intention is to
      review the software, but the material actually concentrates on
      calculations of timing and load, and, when it does move into
      architecture, very rough outlines of subroutines calling each other.

      Private networks, in chapter twelve, covers some history of the rise
      of competition in long distance service, along with a tiny bit of
      technology related to fractional service from digital lines. Chapter
      thirteen extends these concepts with basic information about ISDN
      (Integrated Services Digital Network). Digital switching systems then
      looks at two such switches, the 5ESS and the System 75, in chapter

      Chapter fifteen presents a lot of data, and more than a little
      opinion, on the topic of user interfaces, concentrating on human
      cognitive factors. The politics and legislation of the Bell System
      breakup are covered in chapter sixteen. The review of switching
      paradigms, in chapter seventeen, is presented within an extremely
      limited framework. For example, Thompson states that big networks
      can't be flat--they must be hierarchical. This is contradicted by the
      existence of the Internet, which is very flat and could be flatter, as
      well as new models for wireless networks that could replace most other
      existing network types. Chapter eighteen, entitled "Intelligent
      Networks," discusses enhanced services and the business roadblocks
      that might prevent their being realized. A variety of topics related
      to transmission infrastructure are touched on in chapter nineteen.
      The physics of optical and photonic components are described in
      chapter twenty, with additional material on division and multiplexing
      in twenty one. The final chapter looks to the future, but only in a
      very short range and with limited imagination.

      Each chapter has a set of questions and references. The exercises are
      substantial and challenging (with a few silly exceptions) but do
      require a very solid background in telephone engineering. The
      bibliography contains decent titles although it is sometimes hard to
      see how helpful the materials would be.

      The author has done a great deal of work on this text, and has put
      much of himself into it. In some cases this makes the work much more
      personal and attractive, but in others it becomes difficult to
      separate fact from opinion. There are other problems. Networking
      concepts appear to be seen primarily from telephony and wired
      perspectives, without a broad and encompassing background. The last
      third of the book is roughly divided by topic, but not very organized
      in terms of intent. In fact, a more rigorous structuring of the whole
      book would benefit the work.

      I'm sure this book is an excellent text for Thompson's course, and
      probably for others as well: it contains a great deal of material and,
      in skilled hands, could be presented to best effect. However, the
      readability of the content and the sheer size of the volume still
      cannot guarantee conceptual density. I'm not sure how useful the work
      would be for telecom professionals, even be they telephone engineers.
      I do know that computer and information science students and
      practitioners would likely be bemused. To outsiders, telephony is
      still an arcane art, kept deliberately secret by its practitioners.
      It is unfortunate that this text does relatively little to dispel that

      copyright Robert M. Slade, 2001 BKTLSWSY.RVW 20010126

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