Mobile Phone SIM Cards
Mobile Phone SIM cards are small transportable devices designed to store unique information associated with the subscriber to a mobile phone network service. A mobile phone cannot fully function without a valid SIM card. A SIM’s main purpose is to authenticate the subscriber to the network service provider. A SIM card contains processing and storage capability and stores information such as phonebook entries, text messages, last numbers dialled (LND) and unique information about the subscriber. Moving a SIM card between compatible mobile phone devices automatically transfers the subscriber’s information to a network provider.
Mobile Phone Access Rights.
The SIM card controls access to elements of the device file system, rights being assigned to a subscriber through 4-8 digit Personal Identification Number (PIN) codes. A pre-set number of attempts (usually three) is allowed before further attempts are blocked completely, rendering communications inoperative. Only by providing a correct PIN Unblocking Key (PUK) may the value of a PIN and its counter be reset on the SIM. If the number of attempts to enter the correct PUK value exceeds a set limit, normally ten, the card becomes blocked permanently. The PUK for a SIM may be obtained from the service provider or network operator by providing the identifier of the UICC (i.e., Integrated Circuit Chip Identifier or ICCID). The ICCID is normally imprinted on the front of the SIM or in some cases read from an element of the file system. SIM’s are available in three different size formats. They are: Mini SIM, Micro SIM and Nano SIM.
Mobile Phone SIM Card Forensics.
Is there information stored on a SIM card worthy of data recovery. A mobile phone SIM card contains user specific and network specific data records these records are designed to allow the device to securely connect with a network provider. The mobile phone network service provider maintains these records on operational and offsite servers. A SIM card does not contain sensitive information such as pictures, videos. home address, bank account etc or other details unless you specifically write those details in a text (SMS) message or specify those details in your contact lists. Along with the text messages, the SIM card holds your phone contacts with names, numbers, history of calls including dates and times. This is why law enforcement seeks to gain entry to SIM cards in order to connect criminals to their associates. The SIM card also contains several pieces of information that relate to the security protocols, the network carrier, your Personal Identification Number (PIN), an unblocking code, and the services you use, like applications. Another very important piece of data is the last location of the phone, which is often useful as a part of any investigation. The mobile phone SIM card also stores a number of parameters such as International Mobile Subscriber Identity (IMSI) a code that represents the country, the carrier, and the subscriber. A list of typical codes:-
|Advice of Charge||Governs payments and receipts of your services.|
|Authentication Key||Ki||Recognizes you as the authorized user.|
|International Mobile Subscriber Identity||IMSI||Allows the network to identify the device.|
|Mobile Country Code||MCC||Identifies the country of origin by a two- or three-digit code.|
|Mobile Subscriber Identification Number||MSIN||Ten-digit code that is the link between you and your cellular carrier.|
|Mobile Subscriber International ISDN Number||MSISDN||A code to decipher who you made calls to. You can change this number.|
|Local Area Identity||LAI||As your data travels between communication points, the SIM stores codes about the local networks.|
|Personal Identification Number||PIN||The code you use to lock and unlock the phone.|
|Service Dialling Number||SDN||The numbers used to access your services like voicemail.|
|Service Provider Name||SPN||The name of your cellular carrier.|
|Short Message Service Centre||SMSC||The service center(s) where your text messages are processed.|
|Unblocking Code||PUK||If you enter the wrong PIN too many times, the phone locks. The PUK, retrieved from the carrier, unlocks the phone.|
|Integrated Circuit Card ID||ICCID||The card’s unique serial number.|
|Value Added Services||VAS||The services and applications that you use or pay for, like call waiting or forwarding.|