SIM卡与话机配合使用的一种智能卡,其包含话机的电话号码和订购服务的详细信息,并可用来储存放在电话本中的号码,也可用来存放个人短消息。模拟标准传统的无线信号的调制方法,使得信号能够携带信息。调频和调幅是两种最普通的模拟调制方法。来电显示显示来电的号码,可以让用户在接电话以前准确地知道电话是从哪部电话打来的。电话本话机和SIM卡上均提供了存储区或供用 SIM card Used in conjunction with a smart phone card, which contains the phone’s phone number and ordering service details, and can be used to store the phone book in the number can also be used to store personal short messages. Analog standard Traditional wireless signal modulation method, making the signal to carry information. FM and AM are the two most common analog modulation methods. Caller ID shows the number of the caller, allowing the user to know exactly where the phone was called before answering the call. Both the phonebook and the SIM card provide a memory area or for use