> For the complete documentation index, see [llms.txt](https://gsm.learn-telecom.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gsm.learn-telecom.com/architecture/ms-mobile-station/sim-card-subscriber-identity-module.md).

# SIM Card - Subscriber Identity Module

## MSISDN

Is stored on HLR from operator.

### Decoding MSISDN

<mark style="color:red;">**00 351**</mark> <mark style="color:orange;">91</mark> <mark style="color:green;">000</mark> <mark style="color:purple;">11</mark> <mark style="color:blue;">22</mark>

### Prefixes

National = 0

Internacional = +351 or <mark style="color:red;">00351</mark> (Portugal)

### MCC - Mobile Country Code

<mark style="color:orange;">91 - Vodafone Portugal</mark>

### NDC - Network Destination Code

<mark style="color:green;">000</mark>

**Explanation**:

The section above provides important codes and identifiers related to your mobile network and SIM card.

* **Internacional**: The international dialing code for Portugal.
* **MCC**: Mobile Country Code, specific to Vodafone Portugal.
* **NDC**: Network Destination Code, often used in conjunction with MCC for routing.
* **ICCID**: Identifies the SIM card uniquely.
* **PIN**: Protects your SIM from unauthorized use.
* **PUK**: Unblocks your SIM if the PIN is entered incorrectly multiple times.
* **PIN2**: An additional security code for advanced features.

**ICCID**: The Integrated Circuit Card Identifier is a unique number assigned to your SIM card.

**PIN**: A Personal Identification Number is a security code that protects against unauthorized use of your SIM card.

**PUK**: A PIN Unblocking Key is used to unblock your SIM card if the PIN is entered incorrectly multiple times.

**PIN2**: Similar to the PIN, this is another security code used to access advanced SIM features.

**PUK2**: This is the key used to unblock the PIN2 if it is entered incorrectly multiple times.