Method for implementing fixed network searching user integrated data base using soft exchange

This invention relates to a system and a method for utilizing soft switch to realize inquiry of user centralized database of stationary network, in which, said system is composed of a structure taking the user centralized database SHLR and intelligent service platform as two independent nodes of the service/application layer, the soft switch as the control layer, IP packet network as the loading layer and SG and TG set in each of PSTN as the access layer, said soft switch network as the overlapping network of PSTN is corresponding to a combined junction office with the SSP function independent of the local network PSTN to form a new fixed network structure by inter-connection and inter-communication of SG and TG with PSTN, a mobile network and Xiao ling tong network: SHLR+SS overlapping network. This invention also provides a method for enquiring data by SS.