IP Telephony

Code 3.5.3060.7
Semester 7th
Flow D - Telecommunication Systems and Computer Networks
Category Obligatory by selection
Credits 4
Class Hours - Lab Hours 3 - 1
Lecturers Efstathios Sykas, Konstantina Sakka (T & R Associates),
Links Course's Website
Web Platform Class 1: BigBlueButton


This course has two aspects: the traffic theoretic and the technological one. The technological part covers the basic telephony transmission and switching systems, starting with the description the basic design of telephone sets, historical analog exchanges and in-band signaling systems, local loops and transmission systems like ADSL, PCM (E1/T1), SDH/SONET. Digital exchanges and the underlying technologies for time vs. space division multiplexing in switching matrices and call processing are explored. Introduction to digital telephony systems, i.e. ISDN, the Intelligent Network, and the Common Channel Signaling System No. 7, Voice over IP (VoIP), SIP and H.323 based systems. The theoretical part covers the basic telephony traffic engineering, basic concepts of telephone traffic and congestion metrics (blocking probability, queuing delay, etc), network dimensioning principles (Moe's method). Congestion measures are derived for the typical telephone systems, lost call cleared systems (Erlang-B and Engset formulas) and delay systems (Erlang-C formula). Discussion on the routing principles and their consequences to the statistical description of traffic (overflow traffic, smoothed and peaked traffic). Introduction to the equivalent random traffic method for the engineering of such complex systems.