Abstract: A cordless telephone provides for increased features available at a portable unit that have heretofore been available only at a base unit which combines a cordless telephone fixed station and telephone answering device. The cordless telephone includes a call screening feature which allows a user at the portable unit to monitor incoming messages received over telephone lines as they are being recorded at the telephone answering device without the user having to configure the portable unit in any way during actual receipt of the message. A built-in loudspeaker is incorporated into the portable unit so that the user may easily listen to the incoming messages. Once receipt of the incoming message is completed, amplifier circuitry driving the loudspeaker is turned off. The cordless telephone also includes a caller-ID feature which informs the user at the portable unit of the identity of a preidentified calling party before the call is answered.

Abstract: A cordless telephone system achieves synchronism for each one of multiple portable units to the same communication channel for communicating with a common base unit. The cordless system uses a dual channel process to allow both the freedom to dynamically change channels as needed to avoid interference while simultaneously providing a capability to resynchronize any portable unit with the base unit on a selected active channel. This is achieved through the use of a fixed service channel and an active channel which changes as needed. If a channel change is made during a call, after the call is completed, the base unit returns to the previous active channel and broadcasts a message to the multiple portable units indicative of the new active channel. Also, any portable unit that attempts to communicate with the base unit on the wrong channel and fails to get a response will transmit a message on the fixed service channel requesting the current active channel from the base unit.

Abstract: A cordless telephone provides both basic and enhanced features that are accessible through the combination of a portable unit and an auxiliary recharge cradle, some of these features being heretofore available only at a base unit which combines a cordless telephone fixed station and a telephone answering device. The cordless telephone includes a call screening feature which allows a user at the portable unit to monitor incoming messages received over telephone lines as they are being recorded at the telephone answering device. A loudspeaker is incorporated into the recharge cradle and, while the portable unit is in this recharge cradle, a user may configure the portable unit and cradle in a manner to monitor the incoming messages through the loudspeaker.

Abstract: A location registering apparatus provides for redirecting of telephone calls intended for a mobile station to, for example, a land-line subscriber telephone number through the use of a station registering device and a suitably configured cellular recharger for charging a battery located in the mobile station. In operation, when a user places the mobile station in the cellular recharger, a signal from the cellular recharger and reflective of this action is provided to the station registering device. Upon receiving this signal, the station registering device initiates a call to a location register in the telephone network and reconfigures information for the mobile station in this network so that all calls intended for this mobile station are rerouted to the previously provided subscriber telephone number, for example, the station user's home or office number.

Abstract: A cordless telephone system includes an arrangement wherein multiple portable units operate with a common base unit using the same security code without conflict or confusion. When a portable unit attempts to establish a radio link with the base unit, for example, this originating portable unit generates a random number which is retained by this unit and also transmitted to the base unit. This random number is substituted for the common stored security code, then shared by the base unit and all of the portable units, for creating a temporary unique security code that is known only to the base unit and the originating portable unit. Interference from other portable units attempting to gain access to the base unit while the originating portable unit is actively communicating with the base unit is thereby advantageously prevented.

Abstract: In an ADPCM coder and decoder including a so-called locking-unlocking adaptation speed control, the adaptation speed is locked to a very slow, almost constant, speed of adaptation for voiceband data and partial band energy signals, i.e., tones and tone like signals, and is unlocked to achieve a fast speed of adaptation for speech. When a so-called partial band energy signal is being inputted, the adaptation speed is biased toward the unlocked state and when a transition occurs from a partial band energy signal to another such signal, the adaptation speed is set to the totally unlocked state and coefficients of an adaptive predictor are set to prescribed values. This is done in both the coder and decoder to minimize generation of impulse noise in the decoder output.

Abstract: A bit compression multiplexer (FIG. 2) for a pair of time division multiplexed digital bit streams each one of which includes a plurality of PCM encoded signals deposited in separate and distinct channels of a repetitive frame and signaling bits multiplexed therewith. The PCM encoded signals of successive frames are normally bit compressed (23) into n-bit signals, but periodically the encoded signals of a frame are bit compressed into n-1 bit signals. The bit compressed signals of the pair of bit streams are time division multiplexed (24) with each other, with the multiplexed compressed signals occupying separate and distinct channels of a repetitive frame. The signaling bits are extracted (21) from the pair of digital bit streams and are inserted (24) into predetermined n-1 bit channels of the last-recited repetitive frame. The signaling bits that are placed in a given channel are related to the encoded message signal of that channel.