dual's context. Responding to this shortcoming, researchers from Lucent Technologies' Bell Labs have developed new software technologies that promise to enable users to tightly control how their location information is shared when using location-enabled mobile devices, such as mobile phones and PDAs. The soft- ware, when taken as a whole, provides a framework that will allow users to specify what location information is shared as well as when, with whom, how, and under what circumstances. Bell Labs' Privacy-Conscious Personalization (PCP) framework relies on user preferences to intelligently infer context, such as working or shopping, and then determines with whom location information should be shared. When a user's location or other information is requested, it is analogous to someone making a query of a database. In PCP's case, the request is checked against the user's preferences and filtered through a high-performance rules engine, known within Bell Labs as "Houdini," before any action is taken. Because location and other mobile services require near-real-time performance, this entire process can take a few milliseconds or less. Bell Labs' technology is based on the belief that privacy isn't a "yes or no" question but rather is a spectrum of possible answers based on a wide range of factors and user situations. Today's location-based services have limited capabilities-mobile users can choose to show their location to everyone, only to an explicitly selected group of buddies, or only to authorized officials in emergency situations using the government-mandated Enhanced 911 (E911). Currently available location tracking services are essentially "one size fits all"-users do not have the ability to tailor this capability to meet their indi- vidual preferences. LOCATION-BASED PRIVACY SOFTWARE The PCP framework will enable consumer and business users to specify which individuals, groups, or businesses can see where they are based on the users' preferences. For example, during working hours, field sales representa- t