The iPhone 4S manual is available on the Apple website. Navigate to the support section of the website and use the search feature to find the manual. Alternatively, the same manual is also available on iPod.about.com.
On the Apple website, first click on the Support link on the top right corner of the page. Now, click on the magnifying glass button next to the Support link. Below the search box, under Quick links, click on Manuals. On the next page, click on Browse by Product. In the search box, enter iPhone 4S and hit the return key. The page displays a number of results. To download the manual, click on the third result, iPhone User Guide for iOS 8.4. This guide includes comprehensive details about the iPhone 4S and also serves as a user guide for various other iPhone devices combined into one.
To download the manual on iPod.about.com, first click on Tech Support for iPhones, iPods, and iTunes under iPhone/iPod categories. On the next page, click on iPhone Manual under iPhone and iPod Manuals. The fourth option on the next page gives the link to download the iPhone 4S manual in PDF format. Click on iOS 5 User Guide under iPhone 4S and the manual opens within the browser.