How to Upgrade a First Generation iPhoneby Mario Calhoun
If your iPhone's software is outdated it needs to be updated before downloading third-party applications, as the application can conflict with the phone's software and result in erratic behavior. According to Apple, the original iPhone is able to be upgraded to the 3.1 update, and is not compatible with the 4.0 operating system due to the device's inability to handle the multi-tasking feature in the newer update. The phone's update requires iTunes 8 or later, which is a free Mac and PC-compatible program at the Apple site.
Connect your iPhone to your Mac or PC's USB port via the USB cable.
Open iTunes and select the name of your device in the iTunes window.
Click the "Check for Update" button in the iPhone's preferences window and click "Download and Install."
Click "Next" in the iPhone Setup Assistant, click "Agree" and click "Next" to install the software onto your iPhone.
Click "Done" in the installation window to exit and click "Eject" on the iPhone's tab to disconnect the iPhone.