An attachment to or an integral part of a telephone handset, such attachment or integral part consisting of an appendage connected with the receiver of said handset and designed to function primarily as a pivot, sound conducting device, pivot and rest against the head in a vicinity peripheral to an ear intended as recipient of audio transmission from said handset receiver. Furthermore, said device is designed to function as a spacer to prevent the receiver housing of said telephone handset from ...

An electronic private automatic branch exchange may avoid the need for access trunks and information trunks in the operator complex by utilizing a single stage switching matrix to effect connections between line circuits, trunk circuits, and the operator under control of the common control. To accomplish this the operator line circuits are provided and operator loop circuits as line appearances at the inputs of the matrix. In addition, the common control is provided with recognition circuitry fo...

An acoustic material suitable for use as a speaker edge comprises an expanded plastic and minute collagen fibers wherein the content of the collagen fibers is 15 - 40% based on the weight of the expanded plastic and the length of the fibers is equal to or less than 1 mm.

A call tracing and identification system for use with a public telephone network includes at least one interrogation and digital display circuit associated with a called-party telephone of the network, and an encoder circuit associated with a calling party telephone in the system. In response to an interrogation command initiated by a ringing signal or a line voltage change when the telephone is answered, the encoder circuit generates a series of coded signals and applies the same to the telepho...

Disclosed is a method and apparatus for digitally switching audio signals in a telephone communication system having a plurality of telephone stations with their voice communication channels selectively coupled by way of analog to digital and digital to analog converters through a switch matrix controlled from the output of a stored program controlled computer. The analog audio signals to be inputted to the digital switch matrix are converted to pulse width modulated digital signals, the digitiz...

A bi-directional switching network for a telecommunications exchange in the form of a matrix array of symmetrical switching devices each having many terminations at opposite sides. The switching devices of each row individually have their terminations at one side multipled whereas the switching devices of each column individually have their terminations at the other side multiplied. In a preferred embodiment each switching device includes at least one switching module comprising A-switches, B-sw...

A conference circuit is disclosed for use in a time division switching system which has an incoming and an outgoing time division bus connected by a summing amplifier. During a conference call, a different group of conferee stations is connected to the incoming and outgoing buses by the switching system controller in each of a plurality of time slots dedicated to that call. Output signals from the connected stations are then applied to the incoming bus. The conference circuit is connected to the...

In a large time-space-time division switching network, particularly one employing a multistage space-division switch, one time-division elementary time is too brief to enable transmission of addresses of crosspoints to be completed through all the stages of the multistage switch, and also provide for transmission of the speech sample. To cope with this situation, two successive network elementary times are used, each elementary time being divied into two half-times, i.e., a first half-time and a...

A timing circuit for use in pulse code modulation, time division multiplex switching networks is described. The switching networks are a part of a time division multiplex telecommunication system wherein each call uses the same time slot on the incoming and outgoing lines. The timing circuit has a number of word-organized storage locations equal to the number of PCM words per pulse frame and an equal number of address memory locations individually assigned to the aforementioned storage locations...

The disclosed reframe circuit utilizes common control circuitry to carry out a reframing operation for any, or all, of a plurality of time division multiplexed digital data groups which are out-of-frame. An old data store is used to store a given number (m) of selected data bits, of each digital group, for two frames for framing comparison purposes. A reframe comparator serves to compare, for each digital group, the m bit output of the old data store with m data bits that are two frames later in...