Lost Or Corrupted SIM Data Recovery . . .

In this article brought to you by www.SIMsurprise.co.uk we tell you a little about recovering lost or corrupted data from your SIM card.

Have you ever accidentally deleted one, or more, text message - sent, draft, or received ? Maybe deleted a saved entry in your contacts list ? Perhaps deleted an entry in your Call Register ?

Or perhaps acquired a virus which has corrupted data stored on your SIM card.

There is rarely a "good" time for any of these events to happen.

There are a number of reasons why data on a SIM card becomes inaccessible:

  • Accidental deletion;
  • Deliberate deletion;
  • Virus;
  • Software or hardware failure;

The good news is: it is possible to retrieve (restore) such lost or corrupted data by the use of lost or corrupted data retrieval software packages.


To truly avoid losing irretrievable data, or files, backing up all files to your pc is an excellent idea. Many backup, or transfer, tools are available to transfer data and files from your phone to your pc, and from your pc to your phone.

Data is the term used here to refer to: Text messages, Contact numbers, and other important information stored on your SIM card such as IMSI number, and network service provider. As well as your Calls Register which lists calls made, calls received - including calls received and answered, and calls received but not answered (missed calls) , sometimes referred to as your Call Log.

While technology is moving forward at a rapid pace, changing almost on a monthly basis, there may be some data that cannot be retrieved for various reasons.

As an example, one reason that a deleted text message may not be retrievable is as follows:

When a text message is stored on your SIM card, the text message will be allocated to your SIM card memory.

Perhaps if we explain how text messages are stored on, or saved to, your SIM card we might be able to explain how deleted messages can be retrieved.

Although the following explanation focuses on Text messages - your contacts list (phone directory) will apply a similar principle.

How are text messages stored on a SIM card ?

A SIM card has an area assigned to it, called a file, for the storage of text messages.

This file has a number of areas within the file - perhaps, for simplicity, we shall call these areas folders.

The number of folders is finite - that is, there is a limit to the number of folders that a sim card has - each folder can hold one text message - therefore the number of text messages that your sim card can hold is limited to the number of folders.

When all the folders are filled - in order to receive a new text message it will be necessary to delete an existing message.

Each folder is subdivided into additional areas - again for simplicity we shall refer to these areas as fields.

So, each text message is in a folder, and each folder has its own fields.

These fields are used to store data associated with the text message that is stored in the respective folder - such fields are used to store:

  • Sender's phone number;
  • Date message received;
  • Time message received;
  • Text message itself;
  • State of folder.

The first four of the above five fields are perhaps quite easy to understand to we will not expand on them at this point.

The fifth point above: State of folder - perhaps requires further explanation.

Broadly there are two states - each specific folder can only be in one of the two states at any point in time:

  • In Use;
  • Free.

In use - this simply means that the folder contains a text message.

Free - means that the folder is available to have a text message stored in it.

Free - does not necessarily mean that the folder does not contain a message.

Confused yet ?

Please let us explain.

When you delete a message - either deliberately, or accidentally, one of two things can happen - depending on the make and model of your handset.

Either, the process of deleting the text message will involve only resetting the "State" information from "In Use" to "Free" - leaving all the other fields as they were before the message was "deleted" - the sender's phone number, date received, time received, and text message itself, will still actually be there - you will simply not be able to access this information because you have "deleted" the message by resetting the State field to Free.

Or, when you deliberately, or accidentally, delete a text message, not only will the "State" field be set to "Free", but the other fields: Sender's phone number, Received date, Received time, and text message itself - will be reset to a default value - therefore the text and its associated information is truly deleted

There will be other pieces of data assigned to each text message, telling your SIM card software where in memory each message is stored so that your SIM card knows where to go in its memory to access the message when you go to read the message. Also, stored along with the text message, is information such as the date and time the text message was sent, and the phone number that the text message was sent from.

When you delete a message and the State field becomes Free, this then tells your SIM card that this folder can be used to store a new incoming text message.

So, to recap, depending on your mobile phone handset - when we delete a text message one of two things happen - either:

  • The message is marked as deleted, by resetting the state field only, or
  • The message is actually deleted, by resetting all fields to their default "no message" value.

If method 1 above is used, when a new message arrives and is stored in a folder that has had only the State field reset to Free - the original message and its associated fields will then overwritten with the new message and the new message fields will contain the data for the new message.

In this case, the original message will now most likely be not retrievable.

However, if method 2 above is used to delete a message - unfortunately the deleted message will most likely be irretrievable - irrespective of whether a new message had overwritten the deleted message folder.

Advances in data recovery technology however could well mean that, even in these circumstances, maybe previously irretrievable data could have a greater chance of now being recovered.

How are Contacts stored on a SIM card ?

Similar to your text messages, there is an area of your SIM card that is allocated to storing contacts - Name and phone number.

This area will be divided up into a finite number of sections - one section per contact - once all sections are filled you will not be able to store a new contact until you delete an existing contact.

The author suggests that each section has data associated with the specific section - such as Free, or In Use.

An "In Use" section contains a contact name and phone number.

A "Free" section contains either:

  • No contact name / phone number, or
  • A name and phone number that has been marked as deleted.

A new contact Name and phone number can then be stored in a "Free" section.

Similar to the text message explanation above, a Contact Name and Phone Number that has not been overwritten can most likely be retrieved, whereas a deleted contact Name and Phone Number that has been overwritten could well be irretrievable.

How can data be retrieved ?

There are a number of Data Retrieval software packages, and service providers, being advertised on the Internet.

Maybe a search engine search for "SIM card data retrieval" would return a large number of results.

If you are a "have a go yourself" person, there are a number of software packages available which can be downloaded to your personal computer, or laptop, which allows you to attempt restoration yourself.

These down-loadable software packages are sometimes referred to as "Do It Yourself" packages.

Typically these software packages need to be installed onto your personal computer, or laptop, followed by connecting your SIM card to your personal computer, or laptop, followed by accessing your software package.

As with many, if not all, software package systems there are varying levels of package.

Levels will vary in terms of ease of use and functionality from easy to use or limited functionality to harder to use or greater functionality.

Data retrieval software choices might range in functionality from limited to complex - for example, software packages which are typically used by the general public will not, perhaps, be as complex and functional as packages used by forensic scientists who might be looking for legal evidence.

Many software packages, designed for the general public use, do not require any technical skills or knowledge to operate the data retrieval software package(s). Basically, if you are able to operate a mobile phone the software package should be pose no problem.

The specific order of events will be explained in the software instructions applicable to the specific software package that you purchase.

Each data retrieval software package will have different system requirements such as computer or laptop Operating System, minimum memory level (RAM - Random Access Memory), minimum free hard disk space, and minimum processor class.

For some software manufacturers, there may be different levels of data retrieval software available for differing costs, for example: Basic, and Premium. In this example, the premium package would be of greater functionality and cost than the basic package.

Before purchasing any SIM card data retrieval software package it would be prudent to ascertain the above specifications of your personal computer, or laptop, otherwise installation of the software package may fail, or if the software installs there may be software operation issues.

Another point to remember is that you will also require a SIM card reader which will require your SIM card to be inserted, and a connecting cable (USB) to connect your SIM card reader to your personal computer, or laptop.

Perhaps a good software package bought from a "Bricks And Mortar" store would include a SIM card reader and lead within the software package box.

A software package bought on, and downloaded from, the Internet would not be expected to include the SIM card reader and lead as these are physical goods as opposed to software.

Alternatively, an online supplier might offer the option (at additional cost) for the software package to be posted through the mail on a compact disc whereby it might be possible, again at additional cost, to also purchase a card reader and connecting lead.

If buying the compact disk option, whether on-line or via a "Bricks and Mortar" store, bear in mind that your personal computer, or laptop, will require a compact disk drive.

As an alternative to down-loadable (Do It Yourself") packages, there are also a number of Professional Data Recovery Services advertised providing a service where you will need to arrange for your SIM card, or mobile phone handset, to be taken in to the Service Provider's premises for data retrieval to be undertaken.

Also available is software which can retrieve lost data that has been stored in your mobile phone handset memory.

However, bear in mind that if your mobile phone handset is locked due to entering an incorrect PIN code. (See our article: PIN PAC PUK Explained)

Some data retrieval software is rendered ineffective if your mobile phone handset is locked.

The plus side of this, your handset having to be unlocked before data retrieval can take place, is that if your mobile phone handset is lost or stolen while the phone is PIN protected anyone who attempts to access data can be unsuccessful.

A negative of your handset being unlockable, is that data may not be retrievable even to the legitimate handset owner.

Which is best - downloadable (DIY) software or Professional Data Recovery Services ?

This really depends on a number of factors.

How important is the data which you require retrieving?

If the data is particularly important, either financially, or sentimentally, successful retrieval will be particularly important.

Also, if the lost data is from your phone book - alternative re-entry methods may be quite simple and cost effective, such as manual re-entry - particularly if you have your contact list details recorded elsewhere such as a physical phone book, or diary.

While down-loadable software (DIY) may be generally reliable the functionality may not be to the same level as the software used by, and skills of, the Professional Data Retrieval Service provider who can perhaps increase your chances of successful data recovery.


Before buying a SIM card reader and or downloading data retrieval software - determine whether the data you wish to retrieve is, or was, stored on your SIM card or your mobile phone handset - because different recovery processes will apply.

Scope and purpose of this article

To explain how data retrieval software packages work is beyond the scope of this article.

SIMsurprise.co.uk hopes that this article:

  • Has given some reassurance that data loss can be reversed;
  • Explained the basics of what is required and available to retrieve lost, or corrupted, data.

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