什么是Caller ID[转]

Caller ID

                                       Caller ID
      Your phone rings. A name pops upon on your phone's screen. It's the name and number of the person calling you. Actually, it's the originating telephone number and the name the phone company thinks is the subscriber. The originating telephone number is stored in the originating central office equipment register, which is a database. That number supports a further database lookup, which associates the directory listing, assuming that the originating number is listed (i.e., not unlisted, or "nonpub" for nonpublished). The name and number information is passed through the local and long distance networks, and appears on your Caller ID box or your display telephone between the first and second rings.
      The delivery of Caller ID information assumes several things. First, the entire network of switches must be supported by SS7 (Signaling System System #7). Second, the calling party must originate the call from a single-channel line, rather than a multichannel trunk (e.g., T-1). Third, the originating line/caller must not block the transmission of the information. If all of these criteria are not met, your Caller ID box will display "ANONYMOUS" or "NOT AVAILABLE." Caller ID is one of several CLASS (Custom Local Area Signaling Services) provided by your LEC (Local Exchange Carrier). There generally is both a small installation charge and a monthly charge for Caller ID. Caller ID lets you amaze your parents and scare your technophobic friends, when you answer the phone with something like "Hi, Harry! Great Dictionary!" Caller ID also helps you avoid those dinnertime calls from telemarketers. They always block their numbers. By the way, Caller ID is not the same as ANI, although they often are confused. See also ANI, Caller ID Message Format (for a very detailed explanation), and CLASS.
来电显示
      你的电话振铃。你的电话机屏幕上跳出一个名称。正是呼叫你的人的名称和电话号码。事实上，这正是电话公司认为的该用户的初始电话号码和名称。这个初始电话 号码被存储在最初的市话局设备寄存器，也就是数据库中。这个电话号码支持与号码指南列表相关联的进一步的数据库查询，假设这个初始号码被列在指南里面（即 没有未被列入或者是未被出版“nonpub”）。名称和号码信息通过本地和长途网络传输，出现在你的来电显示器上或者是你的第一次和第二次振铃之间的显示 电话机上。
      来电显示信息的传输假定了几种情况。首先，整个交换机网络必须支持 SS7（系统 7 号信令）。第二，主叫方必须从一个单信道线路而不是多信道中继线（即 T-1）发起呼叫。第三，主叫线路/呼叫方不得阻碍该信息的传输。如果这些标准全部不能满足，那么你的来电显示器上将显示“匿名”或者是“无效”。来电号 码是你的LEC（本地电话公司）提供的几种CLASS（客户本地信令服务）中的一种。通常来电显示有一小笔安装费和月租费。当你接起电话时说 “嗨，Harry，字典编的不错！”时，你会让你的父母吃一惊，也会让你的工学院朋友吓一跳。来电显示功能也会让你避免在吃饭时间接到来自电信市场的电 话。他们总是隐藏自己的电话号码。顺便说一句，来电显示与ANI不一样，尽管这两者总是容易搞混。参见 ANI、Caller ID Message Format （解释的非常详细）和 CLASS。
Caller ID Message Format
      Calling Number Delivery (CND) came about as an extension of Automatic Number Identification (ANI). ANI is a method that is used by telephone companies to identify the billing account for a toll call. Although ANI is not the service that provides the information for CID, it was the first to offer caller information to authorized parties. The CID service became possible with the implementation of Signaling System 7 (SS7). The CID information is transmitted on the subscriber loop using frequency shift keyed (FSK) modem tones. These FSK modem tones are used to transmit the display message in American Standard Code for Information Interchange (ASCII) character code form. The transmission of the display message takes place between the first and second ring. The information sent includes the date, time, and calling number. The name associated with the calling number is sometimes included also. Since the time CID was first made available, it has been expanded to offer CID on Call Waiting (CIDCW) as well. With CIDCW, the call waiting tone is heard and the identification of the second call is seen. In earlier editions of my dictionary, I included the complete formatting, down to individual bits. It's too technical for this dictionary. However, if you want the entire story in all its detail, go to http://www.testmark.com/develop/tml_callerid_cnt.html and read the article on "Caller ID Basics", by Michael W. Slawson of Intertek Testing Services, TestMark Laboratories. Michael has assured me that he will leave his excellent paper on the Web forever.
来电显示信息（CID）格式
      主叫号码传送（CND）是自动号码识别（ANI）的一个扩展功能。ANI是电话公司用来识别长途电话呼叫账单的一种方法。尽管 ANI 并不为 CID 提供信息服务，但是也是第一个为获得授权的被叫方提供主叫方信息的。使用7号信号系统后就可以提供 CID 服务了。使用移频键控（FSK）调制解调器音频可以在用户环路上传输 CID 信息。这些 FSK 调制解调器音频可以以美国信息交换标准码（ASCII）字符代码形式传输显示信息。显示信息的传输发生在第一次和第二次振铃之间。信息传输包括日期、时间 和主叫号码。与主叫号码相关的主叫方名称有时也包括在内。由于是第一次使用，因此对 CID 功能进行了扩展，同时还提供呼叫等待来电显示信息（CIDCW）。使用了 CIDCW，可以听到呼叫等待音，并且第二次呼叫的识别号也可以看到。在我这本辞典的早期版本中，我收纳了完整的格式，直到单个的比特。对这本辞典来说， 太专业了。然而，如果你希望看到所有详细的解释，可以查阅 http://www.testmark.comdevelop/tml_callerid_cnt.html，阅读“来电显示基础”一文，作者是 TestMark实验室 Intertek 测试服务中心的 Michael W. Slawson。Michael 已经向我保证了，他将永远在网站上留下他精彩的论文。