1. Lecture#03 Plain Old Telephone Service The Bonch-Bruevich Saint-Petersburg State University of Telecommunications Series of lectures “Telecommunication networks” Instructor: Prof. Nikolay Sokolov, e-mail: sokolov@niits.ru

2. Forecast (XV century) “The time will come when people from the most distant countries will speak to one another and answer one another”. Leonardo da Vinci

3. History of microphones liquid-based microphone carbon microphone

4. Speech transmission

5. Multiplexing

6. Digital telephony

7. Telephone communications system "Telephone communications system" term is usually refers to base principles of telephone network’s construction, operation and development. These principles usually include the following positions: purpose of the system; supported services; network structure; quality of service ratings; numbering plan; maintenance; equipment requirements; main directions of system development.

8. Main abbreviations PSTN – public switched telephone network, UTN – urban telephone network, RTN – rural telephone network, ISC – international switching centre, (U)LDE – (universal) long-distance exchange, TE – transit exchange, ITN – incoming traffic nodes [TE(I) – transit exchange used as ITN], OTN – outgoing traffic nodes [TE(O) – transit exchange used as OTN], OITN – outgoing and incoming traffic node (equivalent to TE), CO – central office, PBX – private branch exchange, C – concentrator, CE – central exchange, LE – local exchange, SN – service node, SL – subscriber line, TL – trunk lines, TS – telephone set.

9. Model of hypothetic PSTN

10. Hierarchical levels in PSTN

11. Urban telephone network with one CO CCP – cross-connection points

12. Three types of the cross-connection points

13. Central Office Old crossbar exchange Modern digital exchange

14. Perspective PSTN structure with one CO NN – network node

15. Cost of port per user

16. Urban telephone network with several exchanges

17. UTN with incoming traffic nodes

18. UTN with outgoing and incoming traffic nodes

19. Typical structure of the RTN

20. Main components of the area telephone network

21. Connection types in the intraareal telephone communications network

22. Modern principles of the long- distance communication organization

23. Manual switchboard

24. Structure of the existing long-distance telephone network

25. Long-distance exchanges Beginning Present

26. Structure of the perspective long- distance telephone network

27. Connection of the international switching centers GW – gateway (for international communications)

28. Instructor: Prof. Nikolay Sokolov, e-mail: sokolov@niits.ru Questions? Plain Old Telephone Service