TSSN i TSSN About the Tutorial This tutorial will help you understand the different aspects of telecommunication switching systems. It is designed to deliver knowledge about the basic concepts of telephony. Audience A beginner who is interested in the fundamentals of telephony can go ahead with this tutorial, with even little knowledge in communications. Prerequisites It is highly recommended that a reader of this tutorial has prior knowledge about what is telecommunication and how it works. Copyright & Disclaimer Copyright 2017 by Tutorials Point (I) Pvt. Ltd. All the content and graphics published in this e-book are the property of Tutorials Point (I) Pvt. Ltd. The user of this e-book is prohibited to reuse, retain, copy, distribute or republish any contents or a part of contents of this e-book in any manner without written consent of the publisher. 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If you discover any errors on our website or in this tutorial, please notify us at [email protected] i TSSN Table of Contents About the Tutorial ............................................................................................................................................ i Audience ........................................................................................................................................................... i Prerequisites ..................................................................................................................................................... i Copyright & Disclaimer ..................................................................................................................................... i Table of Contents ............................................................................................................................................ ii 1. TSSN – Introduction .................................................................................................................................. 1 Telecommunications ....................................................................................................................................... 1 2. TSSN – Switching Systems ......................................................................................................................... 5 Classification of Switching Systems ................................................................................................................. 5 Electromechanical Switching Systems ............................................................................................................. 6 Electronic Switching Systems .......................................................................................................................... 6 Telecommunication Network .......................................................................................................................... 6 Basics of a Switching System ........................................................................................................................... 7 Folded Network ............................................................................................................................................... 8 Blocking Network ............................................................................................................................................ 9 3. TSSN – Elements of a Switching System .................................................................................................. 10 Switching System ........................................................................................................................................... 10 4. TSSN – Strowger Switching System ......................................................................................................... 13 Automatic Switching System ......................................................................................................................... 13 Rotary Dial Telephone ................................................................................................................................... 14 Signaling Tones .............................................................................................................................................. 17 SWITCHING MECHANISMS ........................................................................................................ 20 5. TSSN – Switching Mechanisms ................................................................................................................ 21 6. TSSN – Common Control Subsystem ....................................................................................................... 30 Common Control Subsystem ......................................................................................................................... 31 7. Touch-tone Dial Telephone ..................................................................................................................... 34 ii TSSN Need for Touch-tone ..................................................................................................................................... 34 How does the Touch-tone Dial Telephone Operate? .................................................................................... 35 8. Crossbar Switching .................................................................................................................................. 40 The Features of Crossbar Switches ................................................................................................................ 40 Crossbar Switching Matrix ............................................................................................................................. 40 Diagonal Crosspoint Matrix ........................................................................................................................... 42 9. TSSN – Crossbar Switch Configurations ................................................................................................... 45 Blocking Crossbar Switches ........................................................................................................................... 45 Transfer Line Support .................................................................................................................................... 47 10. TSSN – Crosspoint Technology ................................................................................................................ 49 Challenges for the Crosspoint Technology .................................................................................................... 49 Electromechanical Crosspoint Technology .................................................................................................... 49 Crossbar Exchange Organization ................................................................................................................... 51 Call Processing ............................................................................................................................................... 51 11. TSSN – Stored Program Control ............................................................................................................... 53 Centralized SPC .............................................................................................................................................. 53 Distributed SPC .............................................................................................................................................. 55 12. TSSN – Software Architecture ................................................................................................................. 56 Process in a Multiprogramming Environment ............................................................................................... 56 Process Control Block .................................................................................................................................... 57 Multi-Stage Networks .................................................................................................................................... 60 13. TSSN – Switching Techniques .................................................................................................................. 63 Network Traffic .............................................................................................................................................. 66 14. Time Division Switching .......................................................................................................................... 68 Space Division Switching ............................................................................................................................... 68 Time Division Switching ................................................................................................................................. 69 Time Division Space Switching ...................................................................................................................... 70 Time Division Time Switching .......................................................................................................................