Abstract: An IP device exchange apparatus includes: a connector that is connected to a first IP phone, a second IP phone, and a third IP phone; a memory for storing a coding scheme obtained by call setting which is negotiated between the first and second IP phones; and a controller that, when receiving a call instruction for call connection to the second IP phone from the third IP phone during communication between the first and second IP phones, employs the coding scheme stored in the memory to perform, between the third IP phone and the IP device exchange apparatus, call setting between the second and third IP phones, while maintaining call connection between the first and second IP phones, thereby changing the call connection between the first and second IP phones to call connection between the second and third IP phones.

Abstract: A computer system 1 has a PBX 2, a terminal device 3, and a management server 4. The PBX 2 has a line controller, an extension controller 2b, an interface, a memory that stores identification information and an enciphered file, a decoder that decodes the enciphered file, a comparator that compares the identification information and the enciphered file decoded by the decoder, and a controller. The terminal device 3 reads the identification information from the PBX 2 and transmits that to the management server 4. The management server 4 has an authenticator that receives a request for authentication when the terminal device 3 logs in, an issuer that issues the enciphered file according to the identification information, and a database that stores the issue date in correlating with the identification information.

Abstract: An IP device exchange apparatus includes: a connector that is connected to a first IP phone, a second IP phone, and a third IP phone; a memory for storing a coding scheme obtained by call setting which is negotiated between the first and second IP phones; and a controller that, when receiving a call instruction for call connection to the second IP phone from the third IP phone during communication between the first and second IP phones, employs the coding scheme stored in the memory to perform, between the third IP phone and the IP device exchange apparatus, call setting between the second and third IP phones, while maintaining call connection between the first and second IP phones, thereby changing the call connection between the first and second IP phones to call connection between the second and third IP phones.

Abstract: A computer system 1 has a PBX 2, a terminal device 3, and a management server 4. The PBX 2 has a line controller, an extension controller 2b, an interface, a memory that stores identification information and an enciphered file, a decoder that decodes the enciphered file, a comparator that compares the identification information and the enciphered file decoded by the decoder, and a controller. The terminal device 3 reads the identification information from the PBX 2 and transmits that to the management server 4. The management server 4 has an authenticator that receives a request for authentication when the terminal device 3 logs in, an issuer that issues the enciphered file according to the identification information, and a database that stores the issue date in correlating with the identification information.

Abstract: In a radio communication system (local radio system) having a plurality of radio cell stations (CS) and a plurality of radio personal stations (PS), when a certain radio personal station (PS) proceeds from a monitoring state to a call state, even during the call, the radio cell station (CS) of interest sends successively the information (slot and frequency information) which is required for the certain radio personal station (PS) to be returned back to the monitoring state to the certain radio personal station (PS) to be stored in the certain radio personal station (PS). By adopting such a procedure, when the call state has been quitted, even if the certain radio personal station proceeds once to a control channel, there is no need of obtaining the information required for the certain radio personal station to be returned back to the monitoring state. Since a time period for obtaining the information is not required, the transition from the call state to the monitoring state is immediately made.

Abstract: When a base station of a digital radiotelephone system receives, through a circuit interface unit of the base station, a call setup message for a radio subordinate unit from a radio control station, an incoming call signal is transmitted to the radio subordinate unit through a radio interface unit of the base station, under control of a control unit of the base station, without performing an acquisition of a circuit communication channel between the radio control station and the base station. Thereafter, when a radio link setup message, an incoming call response, a call proceeding message or an authentication response message is provided by the radio subordinate unit, it is known that the radio subordinate unit is present in a radio area of the base station, and the circuit communication channel is acquired under the management of a communication channel management of the base station.