The UIM card is used to access the CDMA network of China Telecom and is the identification of the access network system. The card surface stores the necessary data for accessing the network, such as the UIM ID, authentication data AKY value, and IMSI number. User Identify Module (UIM) User identify module. It is a smart card used in cdmaOne mobile phones that can be plugged into the corresponding 2G mobile phone to use mobile phone services. The standardization of UIM cards is carried out by 3GPP2 (Third Generation Partnership Program 2). UIM card is a mobile terminal user identification and encryption technology advocated by China Telecom and supported by the International CDMA Organization (CDG). It supports dedicated authentication encryption algorithms and OTA technology (Over The Air), which can update and manage the data on the card through a wireless air interface. The function of the UIM card is similar to that of the SIM card used in GSM mobile phones, which can be used for user identification and communication encryption, and can also store personal information such as phone numbers and short messages. At the same time, the UIM card adopts the convenient use mode of SIM card one card one. Users only need to have a personal UIM card and plug it into any mobile phone equipped with UIM card interface.