The Error 1618 on your Apple iPhone is caused by downloading software while another software package is already downloading on the phone. The iPhone only allows you to download one piece of software at a time. If you have seen this error on your phone, you can get it off by only downloading one software application at a time. If you are stuck in the error prompt, you can turn the error message off by putting your iPhone to sleep. This will cut off the download as well as the error.
Push down on the "Sleep/Wake" button on the top right side of the iPhone when you are prompted with the "Error 1618" message.
Hold the "Sleep/Wake" button down until the slider appears on the iPhone's screen.
Slide your finger across the slider to put the phone to sleep.
Press the "Sleep/Wake" button again to wake the phone up after a couple of seconds of sleep.
Wait for the phone to wake back up with the error message cleared.