Cordless Telephony 3 (CT3) is a cordless telephony( CT) system developed by Ericsson, but not standardized by the European Telecommunications Standards Institute( ETSI). However, this development was the technical basis for the specification of DECT. CT3 operates as a cellular network in the frequency range from 900 MHz to 1 GHz with at 32 or 64 duplex channels.
CT3 uses the TDMA method and Time Division Duplex( TDD) as well as Adaptive Delta Pulse CodeModulation( ADPCM) for voice coding and Gaussian Frequency Shift Keying( GFSK) for modulation. The basic features of CT3, such as the decentralized organization of channel access using the TDMA method or duplex operation, have been incorporated into Digital Enhanced Cordless Telecommunications (DECT). The concept of CT3 is designed for larger private branch exchanges and allows the operation of up to eight base stations and up to 64 handsets via eight frequency channels. Up to 50,000 users can operate on one square kilometer without mutual interference.