Nec Corporation

Nippon Telegraph and Telephone Corporation

Kabushiki Kaisha Toshiba

Nippon Telegraph and Telephone Public Corporation

K.k. Toshiba

Nippon Electric Co., Ltd.

Nippon Telegraph & Telephone Co.

Noboru Saegusa

Akio Yotsutani

Yukihiro Shimura

Koji Ono

Kazuhiro Yoshizawa

Ryoji Kawasaki

Shoji Fuse

Yuji Ohta

Hideki Toyama

Syozi Huse

Koichi Ito

Toshihiro Hara

Akio Toki

Kazuyuki Tate

Kosuke Hashimoto

Shinji Kumataka

Syoji Huse

Ichiro Tamura

Yoshihiko Akaiwa

Isao Sasaki

Masayuki Makino

Kaoru Kato

Tomoshi Sone

Hiroyuki Misawa

Yuichiro Takagawa

Naoyuki Kohyama

Yasushi Hatakeyama

Shoichi Tozuka

Kouzo Kobayashi

Hirokazu Adachi

Naoyasu Nishimura

Masao Ikoma

Ichirou Takase

In a cordless key telephone system in which radio-frequency connections are established between exchange lines and cordless stations in response to a call request, a ringing signal is transmitted in response to an incoming call by containing in it the identification of the line at which the call is terminated. Each cordless station has an array of line keys associated respectively with the exchange lines and an array of line indicators associated respectively with the line keys, and a memory for storing tenant data indicating the lines to which the cordless station is authorized to access. The cordless station examines the tenant data in response to receipt of the ringing signal, and activates one of the line indicators if the indicated line is found in the tenant data, or examines the tenant data in response to an outgoing call originated from the cordless station operating a line key, and allows a connection to be established from that station to an exchange line when the line associated with the operated line key is found in the tenant data.

Cordless key telephone system with multiple tenant facility

In a cordless key telephone system where adjacent service zones having the same control channel are overlapped, forming an unavoidable interference-affected overlapping zone, a main unit initially selects an access unit from each service zone in response to an incoming call from a network and transmits a first alert signal to that unit where it is broadcast to elicit an acknowledgement (ACK) signal from cordless stations. On receiving it, the access unit selects a speech channel, broadcasts a first channel assignment signal on the control channel, and then a first ringing signal on the selected speech channel. The main unit determines whether there is a cordless station falling to respond to the first alert signal. If such a station exists, the main unit selects a first, idle access unit which is located in one of the adjacent service zones. A second alert signal is then broadcast on a control channel from the first access unit. Following receipt of an ACK signal from a cordless station, a second channel assignment signal is broadcast from the first access unit, signalling the identification of a speech channel previously selected by a second, initially selected access unit located in the adjacent service zones. A second ringing signal is broadcast from the second access unit on the previously selected speech channel.

Cordless key telephone system for repeating attempts to alert stations

In a communication control device which is operable in a standby mode or in an active mode and which is located between a cordless telephone set and a subscriber connected to the device through a telephone line to carry out communication therebetween by controlling a plurality of radio speech channels and a control channel assigned to the cordless telephone sets, a monitoring operation is carried out at a monitoring period to search for each idle radio speech channel with the number of the idle radio speech channels counted in the standby mode. The monitoring period is changed in dependence upon the number of the idle radio speech channels. Specifically, control is made so that the monitoring period becomes short when the number of the idle radio speech channels is small. This enables quick search for an idle radio speech channel even when an idle radio speech channel is not found.

Communication control device capable of quickly searching for an idle

In a cordless key telephone system, access units are located in groups corresponding to service areas for broadcasting radio signals on a control channel or on an assigned speech channel to cordless stations. A main controller selects one of the access units for each service area in response to an incoming call from the switched telephone network and sends a first alert signal to the selected access units to cause them to broadcast a recurrent sequence of second alert signals containing the identifiers of standby cordless stations. The second alert signal is received by each standby cordless station and an ACK signal is transmitted if the received signal contains its identifier. The ACK signal is copied by each access unit for transmission to the main controller, whereupon it returns a proceed-to-assign signal if the number of the received copies of the ACK signals is equal to the number of all standby stations. The proceed-to-assign signal is received by the selected access units and a channel assignment signal is broadcast indicating the assigned channel. On receiving it, each station is switched to the assigned channel and one of the stations in each area transmits an end-of-switching signal to cause the access units to broadcast ringing signals containing the identifiers of the alerted stations. In response to a given cordless station going off hook, an off-hook signal is sent from it and copied by the associated access unit for transmission to the main controller, which returns a turn-on signal to allow the given station to activate its speech circuit.

Cordless key telephone system capable of quickly answering incoming calls

A control method for a cordless telephone system including a main apparatus connected to a telephone line and having a line control function, a plurality of stationary apparatuses connected to the main apparatus and each having a radio transmitter/receiver, and portable telephones capable of communicating with the stationary apparatuses through a radio channel. When the main apparatus receives a simultaneous calling request signal from one portable telephone through a given stationary apparatus, it transmits a simultaneous calling request signal to whichever of the other portable telephones are not in use through corresponding stationary apparatuses. The main apparatus then receives, from that responding portable telephone through the corresponding stationary apparatus, an incoming call response signal including an extension number of the responding portable telephone which received the simultaneous calling request signal, and transmits a response display signal including that extension number to the portable telephone which requested simultaneous calling. The portable telephone which requested simultaneous calling displays the extension number of the responding portable telephone.

Control method for cordless telephone which displays identities of

Radio communication system having control method for shortening call

A cordless telephone apparatus having a connecting unit and a cordless telephone set. The apparatus processes a connecting unit call signal sent from the connecting unit and an originating call signal sent from the telephone set by giving priority to either one of the two signals. In a preferred embodiment which gives priority to originating call processing, the connecting unit stops sending a connecting unit call signal and, instead, sends an originating answer signal when an originating call signal with a coincident identification signal is detected during the course of transmission of the connecting unit call signal. The telephone set also sends an originating call signal when a carrier with a coincident identification signal is received. In an alternative embodiment which gives priority to connecting unit call processing, the connecting unit sends a connecting unit call signal on receiving an originating call signal with a coincident identification signal. The telephone set, even during a call originating procedure, stops transmitting an originating call signal and, instead, sends a telephone response signal when it receives a connecting unit call signal with a coincident identification signal.

Cordless telephone apparatus which avoids simultaneous connecting

In a mobile communication system, the base station sequentially scans speech channels and a control channel to monitor call status and detect a call request from a mobile station containing a frame sync and an encoded user's identifier. A successive bit sequence of the call request signal is stored into first and second buffers. A first count value is derived to represent a count of bits stored into the first buffer substantially from the instant an earlier one of two successively detected sync codes is detected, and a second count value is derived to represent a count of bits stored into the second buffer substantially from the instant a later one of the sync codes is generated. When the first and second count values respectively reach a prescribed value, the corresponding one of the buffers is triggered and the bit sequence in the triggered buffer is loaded into a decoder in which it is decoded and checked against a stored version of the user's identifier. If there is a match between them, a signal is transmitted to the mobile station indicating that the call request is accepted. In a modified embodiment, a single buffer is provided and a count value is incremented in response to each of two successively detected sync codes if they are spaced apart by a longer interval, or in response to an earlier one of these sync codes if they are spaced apart by a smaller interval. The bit sequence in the single buffer is loaded into the decoder when the single count value reaches a prescribed value.

Mobile communications system insensitive to false frame sync

Disclosed is a radio channel control method for a system including a main apparatus connected to a telephone line and having a channel control function, a plurality of stationary apparatuses connected to the main apparatus and each having a radio transmitter/receiver, and a portable telephone capable of communicating with the stationary apparatuses through a radio channel. In this method, the main apparatus designates each stationary apparatus in a main or sub state to control communication with the portable telephone and monitors a state signal including information of the main or sub state transmitted from each stationary apparatus. When the state signal from a given stationary apparatus does not coincide with a state of the given stationary apparatus designated by the main apparatus, the main apparatus transmits a state designation signal to the given stationary apparatus to coincide with the state designated by the main apparatus.

Method for controlling a plurality of stationary apparatuses in a

Interconnection control method in cordless telephone system

A radio telephone having a base unit connected to a wired telephone line, a handset unit connectable to the base unit over a radio channel and provided with a hook switch, and a charger for selectively charging the handset unit. The handset unit is automatically controlled to either an on-hook state or an off-hook state when removed from the charger, depending upon the hook state in which the handset unit has been held before the start of charging.

Radio telephone

A cordless telephone system includes a connector connected to a subscriber telephone line and at least one radio telephone set through a radio channel to establish or hold a communication channel between the ratio telephone set and a subscriber. The connector includes a control unit incorporating a timer. The control unit sets the system in a self hold state in which the radio channel is kept connected or a complete hold state in which the radio channel is disconnected on the basis of a hold signal from the radio telephone set, the presence/absence of a radio reception signal within a predetermined period of time preset in the timer, and the type of reception signal.

Cordless telephone system

A new cordless telephone is registered to an existing cordless telephone system by transmitting the product identification number of the new cordless telephone from the access unit of the system to the new cordless telephone, receiving the transmitted product identification number at the new cordless telephone and verifying that the transmitted product identification number is correctly received. In response to the verification, the system and telephone identification numbers of the new cordless telephone are transmitted from the access unit to the new cordless telephone and stored into an electrically erasable programmable read-only memory of this telephone to be used for establishing calls.

Registration of a new cordless telephone to an existing system

A device for recovering a clock from received data which has a different duty ratio is disclosed. The optimum timing of a recovered clock is determined based on the pulse width of received data. A clock is accurately recovered so long as the duty ratio of received data is not greater than .+-.50%.

Clock recovering device

Where a carrier wave is received from a called radio telephone set and where the identification signal of the radio telephone set coincides with a preassigned identification signal, transmission of a paging signal from a base unit is stopped. Even when the identification signals do not coincide with each other, the paging signal is sent continuously over a definite interval. Communication is established only when the signal from a handset to the base station has a predetermined strength and a proper I.D.

Control system of a radio telephone apparatus

Growing community of inventors

Tokyo, Japan

Noboru Saegusa