Research And Realization Of PSTN Number Portability Based On IN Architecture

Number Portability Service is one prime direction of telecommunication development in the future. IN(Intelligent Network)can rapidly and effectively build the system architecture of intelligent services on the traditional communication network,now gradually IN becomes the first choice when telecom operation company wants to provide new services to its customers. Adopting IN technology to realize Number Portability Service can make full use of the current telecom's resources, and avoid equipment resources waste caused by redevelopment.This paper begins with illustration of the development of IN and IN services, introducing the IN's Concept Model,respectively analyses the Service Plane,Global Function Plane,Distributed Function Plane,Physical Plane's responsibilities and their relations,then focuses on the analysis of IN's core part—BCSM(Basic Call State Model),which is basis of separating Call Control from Service. BCSM is consisted of four elements:Point in Call,Detection Point,Transition,Event,they describe a group of call-connection actions and the actions'trigger and transfer process when establishing user's communication channel.After having the detailed research on IN's architecture,the solution of the PSTN(Public Switched Telephone Network) Number Portability Service based on the current IN resources is given,which includes the requirement of the PSTN terminal,the selection of communication signaling,the design of call signaling flow and data table,the detail solution of the call control and service switch.Based on the analysis of the DTMF(Dual-Tone Multi-frequency)signal's characters,this paper proposes two service access modes:"In-Band"and"Out-Band", and realizes the support on the server side. A call control and service switch solution which adopts IN's BCSM method is given,it can flexibly realize the call control and service switch of the two important service cases:the PSTN Number Portability user acts as Caller Party and the PSTN Number Portability user acts as Called Party. Also according to the Number Portability Service's instruction rule,a expanded Number Portability Service instruction design is given. based on the design a optimized signaling solution is proposed,which gives the essential support for the further development of Number Portability Service in the future.