Radio systems are the backbone of any efficient communications center. Most new dispatch centers use a trunked radio system, which is necessary when a large number of mobile radios need to share radio frequencies. A CAD system features enhanced user interface for quicker data entry, storing, and verifying location information entered. Most CAD systems also provide for the entry of businesses, alarms, and hazards associated with addresses. Computer supported telephony applications have emerged as a standard interface that allows any device to communicate with another that is capable of setting up calls, such as a PC and a telephone. Intelligent workstations (PEI and Positron) help control the E-911 call-center environment. Software-based systems allow information to flow seamlessly from the telephony system, through CAD, response, and incident closure. This can help improve dispatch-center response time. Regarding dispatcher headsets, several companies offer a full range of professional and call-center headsets that set the standard in sound quality, durability, and all-day comfort. An air purification system is needed to eliminate the airborne dust and dirt that could damage the sensitive electronic equipment and computers, to clear the odor in the dispatch center, and to reduce the transmission of illnesses from airborne viruses. Mobile data terminals allow field units to send and retrieve data to/from the CAD via trunked radio systems. Furniture options for a communications center vary, but should include enough pieces to house all center equipment. Ergonomic workstation furniture includes such features as sliding monitor trays, articulating task lights, adjustable foot rests, circulating air units, and radiant heaters.