Communications

Telephonic Communications

Signalling Integrity Protection (e.g., Voice Signal Immunity)

No:5321745

Adaptive efficient single/dual tone decoder apparatus and method for identifying call-progression signals

No:5535271

Apparatus and method for dual tone multifrequency signal detection

No:5319703

Apparatus and method for identifying speech and call-progression signals

No:4667065

Apparatus and methods for electrical signal discrimination

No:5519764

Circuit and method for detecting error causing tones in a voice messaging system

No:5333191

Detection of multifrequency tone signals

No:4501003

Dial pulse measurement circuitry

No:5563942

Digital call progress tone detection method with programmable digital call progress tone detector

No:4689760

Digital tone decoder and method of decoding tones using linear prediction coding

No:5172406

Dtmf signal detection apparatus

No:5459784

Dual-tone multifrequency (dtmf) signalling transparency for low-data-rate vocoders

No:6381330

False tone detect suppression using multiple frame sweeping harmonic analysis

No:5533053

Low frequency common mode rejection in a clock circuit

No:6122353

Method and apparatus for detecting a telephone cpe alerting signal

No:6940966

Method and apparatus for detection of a telephone cpe alerting signal

No:5818929

Method and apparatus for dtmf detection

No:5187740

Method and apparatus for telephone call reorigination

No:5862212

Method and structure for detecting a customer premises equipment alerting signal

No:5519774

Method and system for detecting at a selected station an alerting signal in the presence of speech

No:5239574

Methods and apparatus for detecting voice information in telephone-type signals

No:5577117

Methods and apparatus for estimating and adjusting the frequency response of telecommunications channels

No:5214693

Multi-frequency signal receiver and a method of detecting the multi-frequency signal

No:3780230

Multifrequency tone receiver

No:4631361

Programmable ring generator

No:6229889

Robust signaling tone frequency measurement

No:5459781

Selectively activated dual tone multi-frequency detector

No:5263084

Spontaneous caller identification with call-waiting

No:5960075

Switchmode power converters for telephone subscriber line interface circuits

No:5822404

System and method for identifying remote communications formats

No:6115465

System and method for modifying voice signals to avoid triggering tone detectors

No:5467395

Telephone exchange apparatus

No:4219699

Telephone supervision system using dtmf signals

No:5619564

Tone detector with improved performance in the presence of speech

No:5850437

Transmission system with improved tone detection

No:5438618

Vocal frequency suppression apparatus and method

No:5619565

Voice activity detection method and apparatus using the same

No:5598466

Voice activity detector for half-duplex audio communication system

No:5737407

Voice activity detector for half-duplex audio communication system

No:5638436

Voice detection