Relay trees connected to modified connector switches provide call-waiting service on a connector-group basis in step-by-step telephone switching systems. The subscriber's line is connected to an auxiliary line relay which functions to connect the line to the usual line circuit and bank terminals when normal, and to an auxiliary connector bank terminal when the relay is operated. Additional brushes added to the connector allow connection to the auxiliary bank terminal and to the regular bank term...

1. In a system of secret transmission of speech, means to subdivide speech waves constituting a message into a plurality of narrow frequency bands, means to integrate the energy in each band, means individual to said bands to subdivide the integrated energy from each band on a time basis to produce impulses with intervening spaces, and means to variably control said last-mentioned subdividing means individually in accordance with a key unrelated to the message.

This system includes optical fibers (21,26,49,51) which connect subscriber sets (p,n) to an optical interconnection center (59). An optical frequency F.sub.p and a modulation frequency f.sub.p are ascribed to each subscriber p, these frequencies being specific to the subscriber. The set of each subscriber p includes a laser (19) which delivers a wave (22) of frequency F.sub.p and means (9, 12 to 18) to modulate the amplitude of this wave at the frequency f.sub.n ascribed to the subscriber n with...

A wireless telephony system comprising a base station and at least one portable device. The base station employs a ratio frequency (RF) receiver and an optical transmitter. The portable device employs an optical receiver and an RF transmitter.

A circuit for conference telephony using a conventional system for transmission of voice data and having no use for the conventional hybrid station is materialized by this invention using at least two buffer memory circuits provided for each of the frames and adapted to be switched to each other one for input and the other for output, enabling one of the buffer memory circuits to memorize voice data transmitted thereto and, in the meantime, permitting the voice data of the preceding frame memori...

A speech recognition system that detects a similarity between each speech pattern which has already been registered in the system and a speech pattern newly generated in response to the user's utterance made while the system is in a registration mode. The system further provides to the user in the registration mode information representing the detected similarity. The speech recognition system may be incorporated into a telephone apparatus or a radio telephone apparatus, in which a call originat...

A conference system comprises a conference circuit to which a plurality of participants are connected via terminals respective connecting circuits having input and output circuits, the signal from the output circuits being fed to the connecting circuit and signals from the conference circuit being fed lines to the input circuits. The conference circuit has summing amplifiers (10 to 13) whose inputs are connected to the outputs of the connecting circuits so that the output signals from the connec...

A framing system for the receiver in a T-carrier system of the kind in which framing signals are transmitted only in alternate frames. A group of eight time slots is fed to a store and compared with the corresponding eight time slots two frames later. If there is no framing relationship, the circuit steps to the next succeeding group of eight time slots and repeats the comparison. If the timing relationship is found, further comparisons are made at intervals of two frames each. If the framing re...

1. In secret telephony, means to analyze speech message waves into slowly varying currents representative of energy variations in respective portions of the speech frequency band, distributor means for rapidly switching fragments of said currents to line in rotation, a source of masing currents for each of said slowly varying currents, the masking currents each varying in magnitude in random manner, and synchronously operating means for adding masking current from a respective source to each fra...

A system and methods through which incoming calls to and/or outgoing calls from a telephone can be controlled. The present invention utilizes an authorized caller list to determine whether an incoming call should be connected, and a similar list to determine whether an outgoing call should be connected. The present invention can also facilitate the use of new telephone user interfaces, including by iterating through telephone numbers associated with a contact, until communications with the conta...