Digital closed network constructed from a telephone exchange and key telephone system and signal transmission method of the digital closed network

摘要

Each telephone (20) belonging to a key telephone system (KTS) is connected to a telephone exchange (10) and employed as a node for connection to a network device (30) in order to form the closed network for voice, data and video transmission. Voices received from a first telephone are converted into voice packets for transmitting to a second telephone which converts and broadcasts the voice packets to the form of voice signals. - An INDEPENDENT CLAIM is also included for a digital closed network comprising at least one telephone exchange connected with trunk lines/leased lines and having a voice packet converting and restoring function (11), telephones connected to the exchange to form a closed network and network devices connected to one of the telephones to communicate with the exchange.