Design And Implementation Of Interface About Digital Trunk In Embedded IP-PBX System

As the telecommunication evolved very fast,from the early age of the Analog Voice network to the Digit Voice network,then went into H.323 VoIP network and SIP VoIP network etc,different technical telecommunication network platforms coexist and develop continually.The embedded xNode IP-PBX,which core protocol is compatible the Session Initiation Protocol(RFC3261),is a converged communications server which connects the different networks and platforms,and implements interoperation.This thesis,on the basis of the existent xNode IP-PBX system,focuses on the research baout the inter-connection and interoperation between the SIP VoIP network and the traditional ISDN network,and resorts the design and implementation about the digital trunk interface which connects the ISDN network.This thesis mostly includes two parts:hardware circuit about digital trunk(E1/T1)interface and software signal switch system between SIP and ISDN DSS1 protocols.The hardware is PCB board based on the existent xNode IP-PBX system,which embedded processor core chip is instead of the ADSP-BF537 and adds the digital trunk (E1/T1)interface circuit taking into the capability and cost accounts.And a linux kernel and a file system are transplanted into the board.In a word,hardware design follows easy,seeks an excellent proportion between cost and performance.The software,based on the existent xNode IP-PBX system,is a module which performs SIP and ISDN DSS1 Protocols switch.Because the control commands are so different in different platforms,the signal switch plays the key role in the implementation of the xNode IP-PBX.The first chapter introduces Converged Communication,Converged Communications server and background.The second chapter further introduces the reference protocols and standards.The third chapter introduces the hardware circuit design about digital trunk interface and the hardware driver design and realization.The fourth chapter discusses software design and realization about signal switch.The fifth chapter gives the result of testing,and finally draws the conclusion.