Apple on Friday provided the most in-depth look at the iPhone, one week before the device debuts at AT&T and Apple stores across the United States. A 20-minute guided tour posted to the company's Web site showcases the various features the iPhone and explains how to use the touch screen.

While the tour doesn't disclose anything major that hasn't been announced, it does provide the first look at the iPhone's usability and innovative features like visual voicemail and SMS text messaging that works like an iChat session. The built-in iPod functionality is also demonstrated, and the included headphones include a microphone as well. According to the video, the iPhone's built in mail client will support Microsoft Office Word and Excel documents.

More info: Apple iPhone Tour

Apple, iPhone, Smart Phones, 20-Minute, iPhone Tour