Amazon Whispernet works by wirelessly transferring data through a 3G network, allowing users to browse the Internet and purchase content through the Kindle Store. As long as a user is located in an area with AT&T coverage, he can use Whispernet on his Kindle device for free.
Whispersync is a feature of Whispernet that allows a user to synchronize content between multiple Kindle devices that are tied to the same account. For example, Whispersync can monitor the reading progress of an e-book by tracking pages and bookmarks, allowing users to continue reading where they left off even if they switch devices. Although Whispersync is enabled by default on most Kindle devices as of 2015, users can disable the option if necessary.
Through the Whispercast functionality, Whispernet allows companies to automatically update content such as reference documents and manuals wirelessly. Whispernet also includes group management tools that can restrict access to Kindle devices that share the same network, modify device settings or allow users to add their own Kindle devices to the existing wireless network through a centralized interface. Although the Whispernet service didn’t limit the amount of data that users could download initially, AT&T was forced to impose a 50-megabyte monthly limit after some users exploited the service to serve as a wireless hotspot. Once a user reaches the limit, Whispernet limits the browsing experience to Wikipedia and Kindle Store.