说明：  主要是对SIM卡PPT的通信原理、通信安全的介绍，并通过实例编程传输详细对SIM卡的简单应用。并附有代码进行详解，对于这方面通信知识想了解的可以看看。
(This paper mainly introduces the communication principle and security of the SIM card PPT, and transmits the simple application of the SIM card through the example programming. With detailed code, for this aspect of communication knowledge you want to know, you can see.)