Design And Implementation Of Call Transfer Technology Based On SIP-TRUNK

With the popularity of SIP,more and more communication and routing between IPPhone and IP telephone Private branch exchange（IPPBX）begin to use SIP,enterprisesare badly in need of a kind of SIP relay technology to replace the traditional publicswitched telephone network（PSTN）relay:make the enterprises only need to maintenthe SIP network,external telephone communication handed over to the specific Ipphone service providers for forwarding.SIP Trunking technology merges as the timesrequire.At present the existing voice gateway products have provided SIP Trunk basiccommunication functions.In order to meet requires of customers,the telephone serviceprovided by traditional switched telephone network and SIP network also should beimplemented in SIP Trunking gateway.The paper based on the Comware development platform, using agile softwaredevelopment methods,on the background of the research of SIP Trunk call transfertechnology,the original call transfer function of the SIP Trunk voice gateway isimproved, to meet the customer demand for switching business,the new call transferservice of SIP Trunk voice gateway is expanded.The paper mainly includes thefollowings:firstly,SIP protocol and the basic theory and function of SIP-TRUNK areanalysed and studied;secondly,the appropriate process of3PCC is selected to apply tothe SIP-TRUNK voice gateway to handle transfer message,call transfer function forSIP-TRUNK voice gateway is developed to make SIP-TRUNK device pass throughthe call transfer message to the remote device to handle;finally,test environment for thecommunication system is built and a series of tests are taken.The study results have already been applied in product line of H3C Company,andthe feasibility of call transfer based on SIP-TRUNK is proved,and the solid foundationto further study and the application to the Enterprise Unified Communication are built.