(DPI) software lets the operator identify the Websites that users are visiting and the Web services that they're using. The software--or "middleware," as it's called--captures a few packets of data flowing to or from a device on the network, and then quickly analyses the details of the content contained in the packet. This content, called the "payload," could be anything from inbound or outbound Skype videoconferencing data to an OnLive cloud gaming session to a Facebook update.
The carrier can use DPI intelligence to confirm delivery of a guaranteed quality-of-service level for a specific app, such as corporate-level videoconferencing. In this case the software identifies the packets coming from the app, and monitors the amount of time during a given interval that the network cannot convey all of the packets at the promised speed. If there is too much of this "down time," the operator may compensate the customer in some predetermined way.
DPI intelligence can also help the carrier identify revenue opportunities in a given market. Dave Caputo, CEO of network intelligence software maker , gives the example of an operator in Latin America that used DPI data to discover that many of its subscribers were spending a lot of time on ; in fact, they were using it more than they used YouTube (by bandwidth). The operator also learned that the subscribers were willing to pay for a higher-priced data plan if the service could guarantee them unlimited use of the Facebook service every month.
Caputo says that this situation is a win-win for the operator and the subscriber: The operator makes more money per subscriber, while the subscriber enjoys the certainty of not incurring overage charges. Alcatel-Lucent's McDonald likens such a plan to a phone company plan that provides for unlimited night or weekend minutes.
On the dark side, carriers may use DPI software for ""--that is, to capture data for law enforcement from the data streams of "persons of interest." Darker still, critics have cited DPI as a tool that operators may use to detect and then then inhibit or block certain kinds of content--a violation of the principals of .