This clever device allows you to read the deleted messages stored in a mobile telephone sim card. There are two parts to the SIM reading kit: the SIM reader device that holds the SIM and connects to your USB port; and the software CD - this holds the software that reveals deleted text messages. The software will only work on Windows XP or Windows 2000. A pay-as-you-go SIM will usually display 10 texts, a contract SIM will usually display 20 texts. The texts displayed are the last texts saved to the SIM, whether deleted or not. Success varies depending on the phone type that the SIM was used in and the way in which the phone user manages their texts. Best results are obtained from SIMs where texts are regularly deleted. This is because the SIM fills with texts first, and any further texts are stored in the phone.