Update iPhone to iOS 3.0.1 or Greater to Fix SMS Vulnerability
All versions of iPhone running iOS 3.0.1 or earlier are vulnerable to an attack via SMS texting. On 7/31/2009, Apple released iOS 3.0.1 to address the security vulnerability. To install the latest updates from Apple, follow the steps below.
STEP 1: Open iTunes on your PC or Mac.
STEP 2: Attach your iPhone to your computer using the USB cable which came with the iPhone. Depending on your iTunes configuration, the iPhone may begin synching with the computer automatically. If so, allow the sync process to finish.
STEP 3: If your iPhone is not already selected from the Devices list in the left-hand pane, click it to select it.
STEP 4: Click Check for Update.
STEP 5: Click Download and Install.
STEP 6: Click Next.
STEP 7: Click Agree.
STEP 8: The software will begin downloading. An indicator will appear in the left-hand menu pane. Please wait while the software downloads from Apple.
STEP 9: After the software has downloaded from Apple to your computer, the installation will begin automatically. The installation will go through several steps and a series of progress indicators. This may take several minutes. Please wait while all the steps are completed.
STEP 10: After the installation is complete, the following message will appear indicating the process was successful. You may click OK, or simply wait and the message will disappear on its own.
STEP 11: When your iPhone starts up, enter your passcode if prompted. Then, tap the Settings icon.
STEP 12: Tap General.
STEP 13: Tap About.
STEP 14: Next to Version, check to see that the OS version is at least "3.0.1".