Short Message Service (SMS) is a service that digital phones can use to send short messages between phones. SMS messages are more commonly called text messages, and very popular among today's youth.
SMS was originally designed for GSM, but most all of the large digital mobile phone providers provide the ability to send messages to other phones via the SMS.
Most modern phones store the SMS in their internal memory, rather than on the SIM card; in this case forensics should target the phone itself. If the phone does not store the SMS on the SIM card, it can be reconfigured to do so (whether this is possible and how it is done depends on the phone brand and model).
If the phone stores the SMS on the SIM card, forensics should target the card; there is a chance to recover a deleted SMS.
This is possible because some phones will only mark the SMS as deleted (instead of overwriting it with 0 or 1 bits); the text of the SMS will continue to reside on the card until a new SMS is received and the space will be overwritten with the contents of the new message.
SMS Recovery Tools
- pySIM, a "SIM card management tool, capable of creating, editing, deleting, backup and restore operations on your SIM Phonebook and SMS records."
- adafruit industries has a low-cost SIM reader kit that you can get from their website.
- An entry level tutorial that explains the details behind the SMS recovery process
- A video tutorial that shows how an SMS can be recovered (but does not go into the low-level details of the process)