Apple's 4S mobile phone inserted into the calling card is invalid. How should I ask God?

1. Check whether the mobile phone card slot or sim card is damaged: you can try to insert another mobile phone card, and then put the sim card of the mobile phone itself on another mobile phone to see if there is a signal. If the card slot is damaged, it is recommended to replace the card slot. If the sim card is damaged, please replace it in the business hall.

2. Mobile version is not supported: if the mobile version is not supported, you can't use a card, such as the telecom contract version, and you can't use a mobile card.

I. Basic concepts

SIM card is the abbreviation of subscriber identity module, also known as subscriber identity card and smart card. GSM digital mobile phone can only use this card. Digital mobile phone customer information, encryption key and user phone book are stored on the computer chip, which can be used to authenticate the identity of GSM network customers and encrypt the voice information when customers talk.

2.SIM card capacity

Generally, the storage capacity of IC chip of SIM card is 128KB, which can store the following information:

(1) 1000 telephone number and its corresponding name and characters.

(2) 40 groups of short messages.

(3) More than 5 groups of newly dialed numbers.

(4) 4-digit SIM card password (PIN).

There are 16K, 32K, 64K, 128K, 5 12K, 1M SIM cards in the market, as well as professional SIM cards that can provide multimedia services and contactless services, and the capacity can reach M megabytes.