Supporters argue that the use of a body-worn camera allows evidence to be viewed from an unbiased perspective. Corporations are currently working on body-worn camera models that will resolve the technology's limitations such as better audio capturing technology and battery life, to name a few. In recent years police have recruited unmanned surveillance devices such as small throwable robotics and flying drones to conduct reconnaissance in dangerous locations. These devices can be used to identify the presence of a hostage, locate and/or identify subjects, and reveal the layout of a room. The devices do all this by transmitting real-time audio and video to the pilot, giving police an advantage when they cannot directly see a suspect or enter a location where they are needed. Some other uses for this device may be bomb detection, as well as searching suspicious vehicles. Flying drones are also being enlisted to help police in dangerous situations such as a barricaded suspect or a hostage situation. These drones increase safety by providing information that can be used in mapping and planning. These devices equipped with cameras allow officers to get a bird's eye view of a scene in an emergency, allowing responders to safely get much closer to a scene than they could if they went in on foot. Most American police departments are dispatched from a centralized communications center, using VHF, UHF, or, more recently, digitally trunked radio transceivers mounted in their vehicles, with individual officers carrying portable handsets or ear-worn headsets for communication when away from their vehicles. American police cars are also increasingly equipped with mobile data terminals (MDTs) or portable computers linked by radio to a network allowing them access to state department of motor vehicles information, criminal records, and other important information. Most police communications are now conducted within a regional pool of area telecommunicators or dispatchers using 9-1-1 and 9-1-1 telephone taxation. A large number of police agencies have pooled their 9-1-1 tax resources for Computer Aided Dispatching (CAD) to streamline dispatching and reporting. CAD systems are usually linked to MDTs (see above). A variety of national, regional, state, and local information systems are available to law enforcement agencies in the U.S., with different purposes and types of information. One example is the National Law Enforcement Telecommunications System (NLETS), an interstate justice and public safety network owned by the states supporting inquiry into state systems for criminal history, driver's license and motor vehicle registration, as well as supporting inquiry into federal systems, such as the Department of Homeland Security (DHS) 's U.S. Immigration and Customs Enforcement (ICE) Law Enforcement Support Center, the Drug Enforcement Administration (DEA) National Drug Pointer Index (NDPIX), and the Federal Aviation Administration (FAA) Aircraft Registry and the Government of Canada's Canadian Police Information Centre (CPIC).