英语翻译The Third Generation Partnership Project (3GPP) [12] wor

英语翻译The Third Generation Partnership Project (3GPP) [12] works in the standardization of a 3G mobile system based onan evolved GSM core network and WCDMA radio access technologies.This system is the Universal MobileTelecommunication System (UMTS) that will be launched to the market in the near future.independent of the transport technology,allowing it to work over IP and ATM core networks.This evolution ishighly based on the ideas developed in MEGACO architecture.For example,MSC nodes are divided in twoelements,the MSC server –responsible for all signalling and control functions- and the Media Gateway (MGW)–responsible of data transport functions-.Besides,it makes use of other VoIP protocols like H.245 or RTP.§ A new subsystem,named “IP multimedia” (IM),is added to the PS domain,in order to support IP multimediaservices based on SIP.The central entity in IM is the Call State Control Function (CSCF),which is in charge ofcall set-up and termination,routing of incoming calls,address handling,etc.It basically includes much of thefunctionality found on SIP servers (proxies,registrars,etc).One of the main contributions of IM subsystemwill be the use of “SIP phones”,that is,mobile terminals that directly support SIP signalling.