View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by KhartoumSpace DESIGN OF A LAN-BASED VOICE OVER IP (VOIP) TELEPHONE SYSTEM A thesis submitted to the University of Khartoum in partial fulfillment of the requirement for the degree of MSC in Communication & Information Systems BY HASSAN SULEIMAN ABDALLA OMER B.SC of Electrical Engineering (2000) University of Khartoum Supervisor Dr. MOHAMMED ALI HAMAD ABBAS Faculty of Engineering & Architecture Department of Electrical & Electronics Engineering SEPTEMBER 2009 ﺑﺴﻢ اﷲ اﻟﺮﺣﻤﻦ اﻟﺮﺣﻴﻢ ﺻﺪق اﷲ اﻟﻌﻈﻴﻢ iii ACKNOWLEDGEMENTS First I would like to thanks my supervisor Dr. Mohammed Ali Hamad Abbas, because this research project would not have been possible without his support and guidance; so I take this opportunity to offer him my gratitude for his patience ,support and guidance . Special thanks to the Department of Electrical and Electronics Engineering University Of Khartoum for their facilities, also I would like to convey my thanks to the staff member of MSc program for their help and to all my colleges in the MSc program. It is with great affection and appreciation that I acknowledge my indebtedness to my parents for their understanding & endless love. H.Suleiman iv Abstract The objective of this study was to design a program to transmit voice conversations over data network using the internet protocol –Voice Over IP (VOIP). JAVA programming language was used to design the client-server model, codec and socket interfaces. The design was fully explained as to its input, processing and output. The test of the designed voice over IP model was successful, although some delay in receiving the conversation was noticed. This was related to the data network used. The noticed echo could be attributed to the quality of the media used. The study recommended overcoming the above mentioned problems. It also recommended application of the designed programme in a graphical interface form so as to make it easier for non IT specialists. This can make the design of commercial value. v ﻣﺴﺘﺨﻠﺺ هﺪﻓﺖ اﻟﺪراﺳﺔ ﻟﺘﺼﻤﻴﻢ ﺑﺮﻧﺎﻣﺞ ﻻﺳﺘﺨﺪاﻣﻪ ﻓﻲ ﻧﻘﻞ اﻟﻤﺤﺎدﺛﺎت اﻟﺼﻮﺗﻴﺔ ﻋﺒﺮ ﺑﺮوﺗﻮآﻮل اﻻﻧﺘﺮﻧﺖ. اﺳﺘﺨﺪﻣﺖ ﻟﻐﺔ ﺑﺮﻣﺠﺔ ﺟﺎﻓﺎ ( JAVA ) ﻓﻲ ﺗﺼﻤﻴﻢ ﻧﻤﻮذج اﻟﺨﺎدم و اﻟﺰﺑﻮن و اﻟﻤﺸﻔﺮات و اﻟﻤﻨﺎﻓﺬ.و ﺗﻢ ﺷﺮح ﻃﺮﻳﻘﺔ ﺗﺼﻤﻴﻢ و ﻋﻤﻞ اﻟﺒﺮﻧﺎﻣﺞ ﻣﻦ ﻧﺎﺣﻴﺔ ادﺧﺎل و ﻣﻌﺎﻟﺠﺔ و ﻣﺨﺮﺟﺎت اﻟﺒﻴﺎﻧﺎت. ﺗﻤﺖ ﺗﺠﺮﺑﺔ ﻧﻘﻞ اﻟﻤﺤﺎدﺛﺎت اﻟﺼﻮﺗﻴﺔ ﻋﺒﺮ اﻟﺒﺮﻧﺎﻣﺞ اﻟﻤﺼﻤﻢ و آﺎﻧﺖ اﻟﺘﺠﺮﺑﺔ ﻧﺎﺟﺤﺔ، ﺑﺎﻟﺮﻏﻢ ﻣﻦ ﺣﺪوث ﺑﻌﺾ اﻟﺘﺄﺧﻴﺮ ﻓﻲ اﺳﺘﻘﺒﺎل اﻟﻤﺤﺎدﺛﺎت ﺑﺴﺒﺐ ﻧﻮع اﻟﻮﺳﺎﺋﻂ اﻟﺘﻲ اﺳﺘﺨﺪﻣﺖ (ﺷﺒﻜﺔ ﺗﺒﺎدل اﻟﺒﻴﺎﻧﺎت)، آﻤﺎ ﻟﻮﺣﻆ ﺗﺮدد ﻟﻠﺼﺪى. اوﺻﺖ اﻟﺪراﺳﺔ ﺑﻤﻌﺎﻟﺠﺔ اﻟﺴﻠﺒﻴﺎت اﻟﺘﻲ ﺻﺎﺣﺒﺖ اﻟﺘﻄﺒﻴﻖ و اﺳﺘﺨﺪام واﺟﻬﺎت اﻟﺘﻄﺒﻴﻖ ﺳﻬﻠﺔ اﻻﺳﺘﺨﺪام ﺑﻮاﺳﻄﺔ ﻏﻴﺮ اﻟﻤﺨﺘﺼﻴﻦ ﻓﻲ ﺗﻘﺎﻧﺔ اﻟﻤﻌﻠﻮﻣﺎت ﻣﻤﺎ ﻳﺠﻌﻞ ﺗﻄﺒﻴﻘﺎﺗﻪ اﻟﺘﺠﺎرﻳﺔ ﻣﺘﺎﺣﺔ. vi List of Figures FIGURE2.1Simple Switching Network.....................................................4 FIGURE2.2Central witch..........................................................................7 FIGURE 2.3LOOPS, LINES & TRUNKS............................................. 11 FIGURE3.1TCP/IP& OSI MODEL.........................................................19 FIGURE.2Protocol Relationships in H.323.............................................28 FIGURE 4.1 System Architecture ..........................................................32 FIGURE4.2ClientServermodel................................................................33 FIGURE4.2Simplex Flow Chart..............................................................40 FIGURE 5.1 Starting Server....................................................................42 FIGURE 5.2 Starting Client..................... ...............................................43 FIGURE 5.3 example of input signal........................... ...........................44 FIGURE5.4exampleof output signal........................................................45 vii Glossary of Terms VOIP Voice Over Internet Protocol IP Internet Protocol PSTN Public Switched Telephone Network ITU International Telecom Union LAN Local Area Network MAN Metropolitan Area Network FDM Frequency Division Multiplexing TDM Time Division Multiplexing PBX Private Branch Exchange CO Central Office FXS Foreign Exchange Subscriber FXO Foreign Exchange Office SONET Synchronous Optical Network DTMF Dial Tone Multi Frequency ARPANET Advanced Research Projects Agency Network DARPA Defense Advanced Research Projects Agency IAB Internet Architecture Board OSI Open System Interface TCP/IP Transfer Control Protocol/Internet Protocol PPP Point to Point Protocol ICMP Internet Control Message Protocol UDP User Datagram Protocol FTP File Transfer Protocol SMTP Simple Mail Transfer Protocol HTTP Hyper Text Transmission Protocol SNMP Simple Network Management Protocol RSVP Resource Reservation Protocol RTP Real-time Transport Protocol SIP Session Initiation Protocol IETF Internet Engineering Task Force viii Table of Contents Acknowledgements............................................................................iv Abstract.............................................................................................v vi................................................................................................ﻣﺴﺘﺨﻠﺺ List of Figures..................................................................................vii Glossary of Terms............................................................................viii Table of Contents..............................................................................ix CHAPTER(1)INTRDUCTION…………………....…………………….............1 1.1 Background.................................................................................1 1.2 Objectives of the Project...............................................................2 1.3 Expected Outcome.......................................................................2 1.4 Technical Concepts......................................................................2 1.5 Thesis Layout...............................................................................3 CHAPTER(2)SWITCHED COMMUNICATIONS NETWORKS……….......4 2.1 CIRCUIT-SWITCHING NETWORKS……………………………………...5 2.2CIRCUIT SWITCHING CONCEPTS…………………………..................7 2.3The Public Switched Telephone Network…………………..................8 2.4Structure of the Telephone System……………………………………....8 2.5TELEPHONE SERVICE TODAY…………………………………………....9 2.6CO versus PBX……………………………………………………………......9 2.7LOOPS; LINES; TRUNKS; PBX TRUNKS……………………………....12 2.8TRANSMISSION MEDIA………………………………………………......12 2.9TELEPHONY BASICS………………………………………………..........13 2.9.1TELEPHONES COMPONENTS……………………………………......13 2.9.2TELEPHONY SIGNALING……………………………………………....13 2.9.3CALL PROGRESS INDICATORS……………………………………....15 2.9.4ANSWER SUPERVISION SIGNALING……………………………......15 2.9.5FXO & FXS SIGNALING……………………………………………......15 2.9.6E&M SIGNALING…………………………………………………….......16 ix 2.10SOFTSWITCH ARCHITECTURE…………………………………….....16 2.11 PACKET SWITCHING PRINCIPLES………………………………......16 2.12CIRCUIT SWITCHING vs. PACKET SWITCHING………………......18 CHAPTER(3) NETWORK PROTOCOLS ARCHITECTURE…………......20 3.1TCP/IP PROTOCOL SUITE…………………………………………….....20 3.1.1Physical layer……………………………………………………............20 3.1.2Network access layer……………………………………………….......21 3.1.3Internet layer…………………………………………………………......21 3.1.4Transport layer………………………………………………………......22 3.1.5Application layer…………………………………………………….......23 3.2 OSI REFERENCE MODEL…………………………………………........23 3.2.1Physical layer……………………………………………………….........20 3.2.2Data link layer………………………………………………………........20 3.2.3Network layer……………………………………………………….........20 3.2.4Transport layer.........................................................................20 3.2.5Session layer………………………………………………………..........20 3.2.6Presentation layer………………………………………………............21 3.3 Relevant Standards and Protocols……………………………............21 3.3.1Real-time Transport Protocol (RTP)…………………………............21 3.3.2RTP Control Protocol (RTCP)…………………………………............22 3.3.3 H. 323 Standards……………………………………………...............23 3.3.3.1Architecture of H. 323……………………………………...............23 3.3.3.2H. 323 Features for IP Telephony................................................27 3.3.4 SIP PROTOCOL Basic……………………………………..................28 CHAPTER(4)Design and Implementation............... .....…..................33 4.1Defining the Client Server Model…………………...........................34 4.2 Key Components………………………….........................................35 4.2.1CODEC..................... ……………………………….........................35 4.2.2 Socket Interface ………………………………................................35 4.3 Implementation………………………………………..........................35 4.4 Flow Chart..........……………………………………..........................40 Chapter (5) Results Obtained…………………………...........................41 5.1 Running the Program…………………..........................................41 x 5.2 TEST 1…………………………………………………….......................43 5.3 Test 2.....................................…………………….........................44 Chapter (6) Conclusions……........……………....................................46 6.1Comments………………………………………………..........................46 6.2Future Work……………………………………………..........................47 References………………………………………………..........................48 APPENDIX "A" JAVA CODES………........………...........................49 APPENDIX "B" MATLAB Code…………........................................56 xi CHAPTER (1) INTRODUCTION 1.1Background Telephony service today is provided for the most part over circuit-switched networks, which are referred to as Public Switched Telephone Networks (PSTN). This service is known as Plain Old Telephone