除非您从未拥有过手机或智能手机，否则您不太可能没有听说过SIM卡。没有它们，您将无法使用手机给他人打电话或发送短信。您可能知道这一点，但您知道什么是SIM卡以及为什么需要 SIM 卡吗？您是否不确定SIM卡的用途或SIM卡上存储的信息是什么？如果您想知道这些问题的答案以及更多信息，请阅读本文并了解：
什么是 SIM 卡？
SIM 是Subscriber Identity Module或Subscriber Identification Module的首字母缩写词。SIM卡是包含集成电路的小型平板卡，电话公司使用这些集成电路来识别和验证您在其网络上的订阅。换句话说，SIM卡是让移动运营商知道您的电话号码是什么以及您订阅和支付的语音和数据计划的那些小东西。
有两种主要类型的移动网络：GSM和CDMA。GSM来自Global System for Mobile，使用它的手机总是需要使用SIM卡。另一方面，CDMA 手机过去不需要SIM(CDMA)卡(SIM)，但较新的CDMA手机也需要 SIM 卡。
SIM卡有什么用？SIM卡有什么作用？
SIM卡上包含基本信息，移动运营商使用这些信息来了解您的身份并能够在其网络上验证您的手机。存储在SIM(SIM)卡上的最重要的数据可能是：
- 移动国家代码 (MCC)(Mobile Country Code (MCC))和移动网络代码 (MNC)(Mobile Network Code (MNC))是唯一代码，用于告知您的手机连接到的移动网络您的SIM卡（和手机订阅）属于哪个国家/地区。
- 移动用户识别码 (MSIN)(Mobile Subscriber Identification Number (MSIN))是无线运营商用来识别您的手机的代码，以便将其链接到您的电话号码和电话订阅。
- Authentication Key是您的移动运营商分配给您的(Authentication Key)SIM卡的唯一 128 位值，用于授予您访问运营商网络的权限。此密钥存储在SIM卡和网络运营商数据库中。
此外，大多数 SIM 卡还可用于存储您的一些个人数据，因为它们还可以保存：
- 联系人（电话簿）：(Contacts (Phone book):)大多数SIM卡可以存储多个联系人。在现代SIM卡上，限制通常是 250 个联系人。
- 短信（短信）：(SMS messages (Text messages):) SIM卡还可以保存您收到的短信(SMS)。但是，他们可以保存的消息数量远低于联系人数量。通常，SIM卡可以存储大约 32条 SMS(SMS)消息。
同样， SIM(SIM)卡可以容纳的电话簿条目和SMS消息的数量取决于它有多少存储空间（内存）。SIM卡上可用的存储容量取决于发行该SIM卡的移动运营商的决定。在大多数情况下，SIM卡上最多有 128 KB 的内存。这就引出了下一个问题：
SIM卡是存储卡吗？
不，是(Yes)的。SIM(A SIM)卡是一种伪存储卡，因为它内部确实有一些内存。但是，正如您现在所知，该内存用于存储数量有限的电话簿联系人和SMS消息。SIM卡上的内存不能用于保存照片、视频、音乐、文档或任何其他类型的文件。因此，虽然您可以说SIM卡在技术上是存储卡，但在现实生活中，您不能将其用作典型的存储卡，例如 SD 卡(memory card such as an SD card)。
有哪些不同类型的SIM卡？
所有的SIM卡都做同样的事情，并且上面有相同类型的芯片（集成电路）。但是，SIM卡可以有不同的格式和尺寸，以匹配手机上各种类型的SIM 卡(SIM)插槽。这些是当今使用的SIM卡格式：
- 全尺寸 SIM(Full-size SIM)于 1991 年推出，长度为 85.6 毫米（3.37 英寸），宽度为 53.98 毫米（2.125 英寸），厚度为 0.76 毫米（0.030 英寸）。
- Mini-SIM于 1996 年首次出现——其尺寸为 25 毫米（0.98 英寸）×15 毫米（0.59 英寸）×0.76 毫米（0.030 英寸）。
- Micro-SIM于 2003 年推出，长度为 15 毫米（0.59 英寸），宽度为 12 毫米（0.47 英寸），厚度为 0.76 毫米（0.030 英寸）。
- Nano-SIM于 2012 年问世，现在是最常用的SIM卡类型。这主要是因为智能手机制造商更喜欢它更小的尺寸，这在已经塞满集成电路、相机等的智能手机中不会占用太多空间。Nano- SIM的长度为 12.3 毫米（0.48 英寸），宽度为 8.8 毫米（0.35 英寸），厚度为 0.67 毫米（0.026 英寸）。
- eSIM是一种特殊类型的SIM卡，称为Embedded-SIM，于 2010 年推出。eSIM(eSIMs)直接焊接在手机内部，因此您无法将其取出并移动到另一部手机上。只有少数智能手机支持eSIM 卡，通常是来自(eSIM cards)Google（Pixel 4和 4XL）、Apple（iPhone 11、iPhone 11、11 Pro、11 Pro Max、iPhone XS、XS Max、iPhone XR ）的高端设备）、三星(Samsung)（Galaxy Fold、S20、S20+、S20 Ultra、Z翻转(Z Flip)）。
没有SIM(SIM)卡电话可以工作吗？
一个合理的问题：如果手机没有 SIM 卡，您可以使用它吗？(Can you use a phone if it doesn't have a SIM card?)答案是肯定的和否定的。如果您的手机在CDMA网络上(CDMA)工作(States)，例如来自美国(United) Sprint或Verizon的手机，是的，您可以在没有SIM卡的情况下使用您的手机。然而，即使在这样的网络上，如果你想能够连接到 4G LTE ，你也需要一张(LTE)SIM卡，因为这个标准需要SIM卡。如果您的移动运营商使用GSM网络，那么答案从一开始就是不对的，因为GSM无论如何都需要SIM卡。(SIM)
如果您想知道除了拨打或接听电话或短信之外，您是否可以将手机或智能手机用于其他可以做的事情，答案是肯定的。您可以使用任何手机或智能手机在其上玩、玩游戏或运行应用程序，而无需SIM卡。
如果您取出SIM卡并将其放入另一部手机会怎样？
当您从手机中取出SIM卡时，它无法再连接到您的移动运营商。换句话说，您无法通过它接听或拨打电话，也无法发送或接收SMS消息。当您将SIM卡插入另一部手机时，该手机会使用SIM 卡(SIM)向您的移动运营商注册。然后，您可以使用新手机拨打电话和发送消息。此外，如果您在SIM卡上存储了联系人或(SIM)SMS消息，它们将在新手机上可用。同时，它们不再可以从旧的访问。
在手机之间移动SIM(SIM)卡时要记住的重要一点是，不得阻止您插入 SIM 卡的新手机使用它。(SIM)一些移动运营商销售锁定在其网络中的手机和智能手机。在这种情况下，您的SIM卡可能无法在新手机上使用，直到您解锁它。要解锁手机/智能手机，您可能需要联系向您出售手机的移动公司，解锁过程可能会花费一些钱。
同一部手机可以使用两张SIM卡吗？(SIM)
是的，如今销售的许多智能手机甚至是“哑”手机都可以同时使用两张不同的SIM卡。这些设备称为双 SIM 卡(Dual SIM)电话，它们可以使用您插入其中的一张或两张SIM卡来拨打或接听电话。如果您想详细了解双卡(Dual SIM)是什么以及它是如何工作的，请阅读双卡 - 它是什么？双卡是什么意思？双 SIM 卡如何工作？(Dual SIM - What is it? What does Dual SIM mean? How does Dual SIM work?).
您对SIM卡及其功能还有其他疑问吗？
我们希望我们能够明确回答您有关SIM卡的问题。关于SIM(SIM)卡或它们的用途，您还有什么想了解的吗？如果您这样做，或者您有什么要添加到我们的文章中，请随时在下面的部分中发表评论。
What is a SIM card & What does it do?
Unless you've never had a phone or a smartphone, it is unlikely that you haven't heard about SIM cards. Withoυt them, you can't usе your phone to call or send text messages to people. Yоu might know this, but do you know what a SІM card is and why уou need one? Do you have uncertainties regarding what SІM cards are used fоr, or what infоrmation iѕ ѕtored оn a SIM cаrd? If you want to know the answers to these questions and more, read this article and find оut:
What is a SIM card?
SIM is an acronym for Subscriber Identity Module or Subscriber Identification Module. SIM cards are small flat cards that contain integrated circuits used by phone companies to identify and authenticate your subscription on their networks. In other words, SIM cards are those small things that allow mobile operators to know what your phone number is and what voice and data plans you're subscribed to and paying for.
There are two major types of mobile networks out there: GSM and CDMA. GSM comes from Global System for Mobile, and phones that use it always require the use of a SIM card. CDMA phones, on the other hand, did not require a SIM card to work in the past, but newer CDMA phones need one too.
What is a SIM card used for? What does a SIM card do?
SIM cards hold essential information on them, used by the mobile carriers to know your identity and be able to authenticate your phone on their networks. Probably the most important data stored on a SIM card are:
- Mobile Country Code (MCC) and Mobile Network Code (MNC) are unique codes that tell the mobile networks to which your phone connects what country your SIM card (and phone subscription) belongs to.
- Mobile Subscriber Identification Number (MSIN) is a code that's used by the wireless carriers to identify your phone so that it can link it to your phone number and phone subscription.
- Authentication Key is a unique 128-bit value assigned to your SIM card by your mobile operator, used for granting you access to the carrier's network. This key is stored both on the SIM card and on the network carrier database.
Furthermore, most SIM cards can also be used for storing some of your personal data, as they can also hold:
- Contacts (Phone book): Most SIM cards can store a number of contacts. On modern SIM cards, the limit is usually 250 contacts.
- SMS messages (Text messages): SIM cards can also hold SMS messages that you receive. However, the number of messages they can save is much lower than the number of contacts. Typically, SIM cards can store about 32 SMS messages.
On that same note, the number of phone book entries and SMS messages that a SIM card can hold differs depending on how much storage space (memory) it has. The amount of storage capacity available on a SIM card varies according to what the mobile carrier that issued that SIM decided. In most cases, SIM cards have up to 128 kilobytes of memory on them. Which brings us to the next question:
Is a SIM card a memory card?
No, and Yes. A SIM card is a pseudo-memory card, as it does have some memory inside. However, as you know now, that memory is used for storing a limited number of phone book contacts and SMS messages. The memory on a SIM card cannot be used for saving photos, videos, music, documents, or any other type of file. So, although you could say that a SIM card is technically a memory card, in real-life, you cannot use it as a typical memory card such as an SD card.
What are the different types of SIM cards?
All SIM cards do the same thing and have the same kind of chips (integrated circuit) on them. However, SIM cards can have different formats and dimensions, matching the various types of SIM slots found on phones. These are the SIM card formats used today:
- Full-size SIM was introduced in 1991 and has a length of 85.6 mm (3.37 in), a width of 53.98 mm (2.125 in), and a thickness of 0.76 mm (0.030 in).
- Mini-SIM appeared for the first time in 1996 - its dimensions are 25 mm (0.98 in) × 15 mm (0.59 in) × 0.76 mm (0.030 in).
- Micro-SIM was launched in 2003 and is 15 mm (0.59 in) in length, 12 mm (0.47 in) in width, and 0.76 mm (0.030 in) in thickness.
- Nano-SIM came into existence in 2012 and is now the most commonly used type of SIM card. That's mainly because smartphone manufacturers prefer its smaller dimensions, which don't take a lot of space in the smartphones already crammed with integrated circuits, cameras, and others. Nano-SIMs have a length of 12.3 mm (0.48 in), 8.8 mm (0.35 in) in width, and 0.67 mm (0.026 in) in thickness.
- eSIM is a special type of SIM card called Embedded-SIM that was launched in 2010. eSIMs are soldered directly inside phones, so you can't take it out and move it to another phone. There are only a few smartphones out there that support eSIM cards, typically higher-end devices from Google (Pixel 4 and 4XL), Apple (iPhone 11, iPhone 11, 11 Pro, 11 Pro Max, iPhone XS, XS Max, iPhone XR), Samsung (Galaxy Fold, S20, S20+, S20 Ultra, Z Flip).
Can a phone work without a SIM card?
A legitimate question: Can you use a phone if it doesn't have a SIM card? The answer is both yes and no. If your phone works on a CDMA network, like those from United States' Sprint or Verizon, yes, you can use your phone without a SIM card. However, even on such networks, you need a SIM card if you want to be able to connect to 4G LTE because this standard requires SIM cards. If your mobile carrier uses GSM networks, then the answer is no right from the start, as GSM requires SIM cards no matter what.
If you are wondering whether you can use a phone or smartphone for other things it can do besides making or receiving phone calls or text messages, the answer is yes. You can use any phone or smartphone for playing, gaming, or running apps on it, without having a SIM card.
What happens if you take out your SIM card and put it in another phone?
When you take the SIM card out of your phone, it can no longer connect to your mobile carrier. In other words, you can't receive or make calls from it, nor send or receive SMS messages. When you insert the SIM card into another phone, that phone uses the SIM to register to your mobile operator. Then, you can use the new phone for calls and messages. Also, if you have contacts or SMS messages stored on the SIM card, they become available on the new phone. At the same time, they're no longer accessible from the old one.
What's important to remember about moving SIM cards between phones is that the new phone in which you're inserting your SIM must not be blocked from using it. Some mobile operators sell phones and smartphones that are locked into their networks. In such cases, your SIM card might not work on the new phone until you unlock it. To unlock a phone/smartphone, you'll probably have to contact the mobile company that sold it to you, and the unlock procedure might cost some money.
Can you use two SIM cards in the same phone?
Yes, many smartphones and even "dumb" phones sold these days can use two different SIM cards simultaneously. These devices are called Dual SIM phones, and they can use one or both SIM cards you insert in them to initiate or to receive phone calls. If you want a detailed explanation of what Dual SIM is and how it works, read Dual SIM - What is it? What does Dual SIM mean? How does Dual SIM work?.
Do you have any other questions about SIM cards and what they do?
We hope that we managed to give clear answers to your questions about SIM cards. Is there anything else that you might want to know about SIM cards or what are they used for? If you do, or if you have something to add to our article, feel free to write a comment in the section below.
