China Unicom mobile phone card

China Unicom mobile phone cards include SIM cards and USIM cards: 1. SIM card (Subscriber Identity Module): User identification card, which is the personal information card of GSM mobile phones. It stores user data and authentication. The method and key can be used by the GSM system to authenticate the user's identity. At the same time, users complete the connection with the system and the exchange of information through it. 2. The USIM card is a third-generation mobile phone card that has both 2G and 3G subscriber identification card functions. It is fully compatible with 2G terminals and services and has the characteristics of high security, fast download speed and large capacity. The 128K USIM card can store 50 text messages, 500 contact phone numbers and 200 email addresses.