在当今世界，手机已经成为我们生活中不可或缺的一部分。手机中使用的用户识别模块 (SIM)卡主要用于通话、上网和发送消息。这些 SIM 卡有多种变体，例如 32K、64K、128K 和 256K。这些信息通常印在卡片上。这代表特定 SIM 卡的内存。
“K”代表卡上存在的千字节内存。早期版本的 SIM 卡只有 2G 连接(32K 卡)。随着时代的变迁，更新的技术应运而生，需要更新更好的具有更大存储空间的 SIM 卡。较新的版本用于 3G、4G 和 LTE 互联网连接。最新版本、128K 及更高版本具有跟踪系统，以防手机丢失。较新的版本更先进，具有更多功能、更高速度的互联网连接和更多存储空间。
32K和128K SIM卡的区别：
| S.No. | 32K | 128K | |||
|---|---|---|---|---|---|
| 1. | It was introduced during 1990s. | It was introduced after 2003. | |||
| 2. | It has 32 kilobytes of storage memory. | It has 128 kilobytes of storage memory. | |||
| 3. | It can be used to store contact information of about 250 people. | It can be used to store contact information of about 600 people (approximate value, as it depends upon the provider). | |||
| 4. | It does not have auto roaming feature. | It has auto roaming feature. | |||
| 5. | It does not have feature of auto accessing the social media accounts. | It has the feature of auto accessing the social media accounts. | |||
| 6. | It does not have SMS lock. | It has an SMS lock for unauthorized access. | |||
| 7. | It is used for accessing 2G data services. | It is used for accessing 4G and later versions of data services. | 8. | It cannot be used for tracking phone in case of theft or loss. | It can be used to track the phone in case it gets lost. |