# Description

The format of the ICCID is: MMCC IINN NNNN NNNN NN C x 

MM = Constant (ISO 7812 Major Industry Identifier) 

CC = Country Code 

II = Issuer Identifier 

N{12} = Account ID ("SIM number") 

C = Checksum calculated from the other 19 digits using the Luhn algorithm. 

x = An extra 20th digit is returned by the 'AT!ICCID?' command, but it is not officially part of the ICCID.

**PREPAID**

Prepaid cards already have a tax plan assigned to them

**POSTPAID**

#### SIM Card Structure

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SIM cards hold a profile mapped by the network operator, these cards have a storage capacity 8k,16k,32k128k,etc...

MF - Master Files

DF - Dedicated Files

EF - Elementary Files

Standards : GSM 11.11 - [3GPP 51.011](https://www.etsi.org/deliver/etsi_TS/151000_151099/151011/04.15.00_60/ts_151011v041500p.pdf)

#### SIM Card Profile

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Network Requirements

* MCC / MNC
* IMSI
* ICC-ID
* SMS Parameters 

Marketing Requirements

* Phonebook
* Number of Short Messages
* Service Dialing Number (Customer Care Numbers
* Mailbox Number

Business Requirements

* Roaming Partner List
* PIN Handling

**ICC-ID**

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ICC 

* **SIM** - Single IMSI or Dual IMSI
* **RUIM** - Single CDMS or Combo CDMA+GSM

ICC-ID is defined by **ITU-T E.118**

The ICC-ID has 19 digits and calculated using Luhn algorithm.

89-91-15-100-000000011-8

89 - Tele

91 - CC

15 - MNC

100 - Vendor

000000011 - Serial Number

8 - Checksum

**IMSI**

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**I**nternational **M**obile **S**ubscriber **I**dentity

The IMSI has 15 digits and is unique across all globe and indicates the home network of the subscriber.

MCC + MNC + MSIN = IMSI

MNS + MSIN = NMSI

**SIM Keys**