Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A radio communication system of a multi-channel access type in which an idle one of a plurality of radio channels is detected to perform transmission and reception of voice signals, data signals or the like. In the present system, in the case where a base unit receives an incoming call from a wired line, the base unit transmits to a plurality of radio terminal units a speech channel designation signal as well as a representative radio terminal designation signal specifying a representative radio terminal unit from the plurality of radio terminal units, and when receiving a channel switching completion signal from the representative radio terminal unit, the base unit transmits a signal for generation of ringing tones to the plurality of radio terminal units at the same time to cause the plurality of radio terminal units to generate the ringing tones at the same time.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: An interconnection control method in a cordless telephone system having a connection unit connected to a subscriber line and a plurality of radio telephone sets connected through a radio communication circuit to the connection unit. Each of the radio telephone sets in a signal transmits, in a signal transmission mode, a calling signal containing group identification information and individual identification information. The connection unit, only when the received group identification information coincides with a predetermined content, returns a calling answer signal containing group identification information and individual identification information of the transmitting radio telephone sets and then establishes a speech channel between the connection unit and the other party telephone set.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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%.

Abstract: 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.

Abstract: A cordless telephone system constituted by a switching station connected to a cable telephone exchanger and at least one telephone set connected to the switching station via a plurality of radio channels. The switching station has a controller which scans the radio channels and selects a nonused radio channel in response to a calling signal from the telephone exchanger, a signal generator for calling a telephone set, a signal detector for detecting a response signal from the telephone set, and a transmitter. The controller changes the number of radio channels to be scanned in accordance with the frequency of use of the radio channels and the transmitter sends a signal representing a changed number of radio channels. Each telephone set has a controller for scanning the radio channels, a signal detector for detecting the calling signal and the signal representing the number of channels from the switching station, and a transmitter for sending a response signal to the switching station.

Abstract: A portable unit that may be called from a base station through a radio control channel by a succession of terminating call signals that is sent through the control channel from the base station to the portable unit for a first or restricted time duration (T.sub.1), selected in consideration of a battery saving period of a battery saving operation carried out in the portable unit. Within the battery saving period, the portable unit is put into transient active and inactive states during a first time interval and a second time interval, respectively. Selection is made so that the first time duration is longer than the second time interval to receive at least one of the terminating call signals within the first time duration in the portable unit. The base station monitors an acknowledgement signal for a second time duration (T.sub.2) after the lapse of the first time duration and interrupts the control channel when the acknowledgement signal is not received within the first and the second time durations.

Abstract: In a radio telephone system comprising a radio telephone set utilizing a rechargeable battery, and a base unit connected to the radio telepone set through a radio channel for exchanging a speech signal between the radio telephone set and a wired telephone line, there are provided a detector for detecting the charged state of the battery, a terminating device responsive to the output signal of the detector for terminating the radio channel between the radio telephone set and the base unit.

Abstract: A portable unit that may be called from a base station through a radio control channel by a succession of terminating call signals that is sent through the control channel from the base station to the portable unit for a first or restricted time duration (T.sub.1), selected in consideration of a battery saving period of a battery saving operation carried out in the portable unit. Within the battery saving period, the portable unit is put into transient active and inactive states during a first time interval and a second time interval, respectively. Selection is made so that the first time duration is longer than the second time interval to receive at least one of the terminating call signals within the first time duration in the portable unit. The base station monitors an acknowledgement signal for a second time duration (T.sub.2) after the lapse of the first time duration and interrupts the control channel when the acknowledgement signal is not received within the first and the second time durations.

Abstract: A mobile radio communication system having a plurality of fixed stations respectively connected to a plurality of subscriber's lines extending from a telephone exchange, and a plurality of mobile stations linked with the fixed stations through radio channels. Each of the mobile stations effect speech via one of the fixed stations. The system comprises means provided for each fixed station for transmitting rate charging information from the telephone exchange to a mobile station under speech, and rate collecting means provided for each mobile station and being responsive to the rate charging information to vary its content.