What is a Calling Card?

Making a call is a convenient way for people to communicate with each other. By telephone, especially international long-distance calls, two parties that are thousands or even thousands of kilometers apart can be connected, which not only saves the labor of long-distance travel, but also saves time and Travel expenses have greatly improved work efficiency.

phone card

Chinese name: phone card
use: Magnetic card controls call and pay phone

by: Telephone offices installed in public places
Substitute: Magnetic card for paying phone charges in cash

sim Phone card sim card overview

The SIM card is called "Subscriber Identification Card". It is actually a smart card containing a large-scale integrated circuit, which is used to register important data and information of the user. One of the most important functions of a SIM card is authentication and encryption. When a user moves to a new area to make or receive a call, the switch must authenticate the user to determine whether it is a legitimate user. At this time, the SIM card and the switch use the authentication algorithm at the same time to calculate the authentication key and the 8-bit random number. If the calculation result is the same, the SIM card is recognized, otherwise the SIM card is rejected and the user cannot make a call. The SIM card can also use encryption algorithms to encrypt the conversation to prevent eavesdropping.

Phone card function embodiment

Specifically, its function mainly reflects the following aspects. The data stored in the SIM card can be divided into four types: the first type is fixed data. This type of data is written by the SIM card center before the mobile phone is sold, including the International Mobile Subscriber Identity (IMSI), authentication key (KI), authentication and encryption algorithms, and so on. The second type is temporarily stored data about the network. Such as location area identification code (LAI), mobile subscriber temporary identification code (TMSI), public telephone network code forbidden to access, etc. The third category is related business codes, such as personal identification code (PIN), unlock code (PUK), and billing rates. The fourth category is the telephone directory. Almost all user data is stored in the SIM card, so the SIM card is also called "user data identification card". The SIM card is divided into a large card and a small card. The small card is called an "plug-in SIM card", which is the chip on the large card.

Phone card password introduction

In order to prevent the theft of the mobile phone after being lost, each SIM card can be set with a password, which is a personal identification number (PIN), which is used to lock the SIM. The initial PIN is provided with the SIM card, and is generally set to 1234. Users should change it to a password they are familiar with in a timely manner. Only when the user enters the correct password can the phone enter the normal use state. Enter the wrong personal password three times in a row and the phone will lock the SIM card. To unlock, you must use an unlock code (PUK), which is usually provided with your SIM card. If the SIM card is locked and you forget the unlock code, or the SIM card is lost, you need to bring your account opening information and bring it to the local wireless business office to unlock or report the loss.

PIN2 is the password used to access the subordinate functions (such as call charging function) under the SIM card. If the PIN2 code is entered incorrectly three times, the SIM card will also be automatically locked. At this time, you must enter the PIN2 code unlock code (PUK2). If your PUK or PUK2 code is entered incorrectly 10 times in succession, the SIM card will be permanently locked and you can only replace the SIM card.

STK Phone card STK

Another term that often appears at the same time as the SIM card is "STK". STK is the English abbreviation of "SIM card Tool Kit", which means "SIM card development kit". To use mobile value-added services, such as mobile banking, mobile stock trading, and SMS on demand, all require the replacement of ordinary mobile SIM cards with STK SIM cards. STK can be understood as a small programming language for developing value-added services, which allows smart card-based user identification modules (SIM cards) to run their own application software. STK technology provides a developable environment for SIM card value-added services, that is, a simple and easy-to-operate development platform. There are five main types of STK smart cards: memory cards, processor cards, e-wallets, security cards, and Java cards.

PIN Calling card PIN

When you buy a SIM card, you will get a 4-8 digit PIN code (personal identification number) and a PUK code (personal unlock code). The acquisition of the PUK code depends on the system operator. If the SIM card allows it, you can turn off unlocking.

The PIN is the code to access the channel and can activate the user's appointment function. If you make a mistake three times, the SIM card will be locked automatically, and you must enter the PIN decoding code (PUK). PIN2 is used to enter the subordinate functions (such as call charging function) of the SIM card. The password is 4-8 digits. If the PIN2 code is entered incorrectly three times, the SIM card will be automatically locked. You must enter the PIN2 code unlock code (PUK2).

The initial value of the PIN code is generally 1234, which can be changed by the user. The steps are as follows:

1. Select the SIM card lock in the security function directory.

2. Select a new PIN.

3. Enter the original PIN and press YES.

4. Enter the new PIN and press YES.

5. Enter the new PIN again and press YES.

If you enter the wrong PIN three times in succession, the screen displays:

PUK:

1. Enter PUK and press YES.

1. Enter the new PIN and press YES.

3. Enter the new PIN again and press YES.

If your PUK or PUK2 code is entered incorrectly 10 times in succession, the SIM card will be permanently locked and you can only replace the SIM card.

When using a SIM card, prevent excessive pressure or bending, so as to avoid data loss or confusion in the card; pay attention to the metal contacts on the card to keep it clean and avoid contamination of dust. The SIM card should not be operated in an environment higher than 80 ° C or lower than -20 ° C. Do not pull the card out of the phone often. Before removing or inserting the phone, turn off the power of the phone. To prevent the phone from being stolen, please Do not store the SIM card with your personal password (PIN) and unlock code PUK.