Design Of Unstructured Supplementary Service Data Center

With the rapid growth of Chinese economy and communication, China holds the most mobile subscribers in the world. The wireless data service based on the mobile phone grows quickly. According to statistic, short message service brings the carriers several hundred million RMB incomes. Value added service has been developing emphasis of mobile carriers.With the increasing and diversification of users' requirement, the shortcomings of services which are based on store-and-forward appear gradually, such as: time delays, insecurity, inconvenient interaction. Due to such shortcomings, many attracting service can't be deployed, such as: payment, online-charging, guessing game.Unstructured Supplementary Service Data (USSD) is a technology unique to GSM. Other than store-and-forward technology, there are no above shortcomings. It can works as new type service platform, providing new value added service.The author participated in the designing of USSDC ( Unstructured Supplementary Service Data Center), designed and integrated the hardware platform of the signal access part. He took charge of developing signal access part software.This paper introduces, based on the technical specification, how to design and integrate hardware platform, and model software by UML (Unified Modeling Language).This paper also introduces the features of USSD and the MAP (Mobile Application Part) signal flow between USSDC and HLR (Home Location Register) and UAP (USSD Application Protocol) signal flow between USSD center and SPs (Service Provider) and how to setup a USSDC.