Abstract: A system for permitting a user having a personal directory number (PDN) to use a virtual terminal identified by the PND from any of said telephone terminals that the PDN is linked with. If a request for a virtual terminal assignment and the ID of a user are received from one of the terminals, a PDN linked with the ID in personalized feature data is associated with the TDN of the terminal. Thereafter, if a virtual terminal for the PDN linked with the TDN of the terminal is requested from the terminal, the terminal is associated with personalized feature data identified by the PDN and key data associated with the PDN and the TDN to make the terminal in a personal mode of the PDN. In response to a reception of call processing data from the terminal, a call processing is performed on the basis of the personalized feature data, the key data, and terminal data identified by the TDN for specifying a type of the terminal.

Abstract: A conference speech-channel forming method and its conference telephone system, in which an extension telephone set to be operated by an operator as the chairman of a conference is connected in a predetermined logical manner through a private branch exchange to a plurality of extension telephone sets to be operated by a plurality of operators as the participators of the conference to form conference speech channels between these extension telephone sets. That is, the conference speech channels are formed so that (a) a voice signal issued from the extension telephone set of the chairman operator is parallelly transmitted in one way to all the plurality of extension telephone sets of the plurality of participator operators, and (b) voice signals issued from the plurality of extension telephone sets of the participator operators are added together at a voice adder circuit and then transmitted to the extension telephone set of the chairman operator.