The new Tempest2400 wireless intercom system from Clear-Com operates in a license-free frequency band where interference from other wireless products isn't likely, according to the company. By using the 2.4-GHz Frequency Hopping Spread Spectrum (FHSS) plus TDMA technology, the Tempest2400 RF scheme avoids the need for licensing and frequency coordination. Once registered to a base station, a belt pack can roam freely within a single zone without further configuration. Each base station supports up to five full-duplex, four-audio-channel, digital wireless belt packs. Price: $15,000 (base station and five belt packs). Clear-Com Communications. 510-337-6600. www.clearcom.com.