Casio Phonemate, Inc.

Alex Nirshberg

Mark J Karnowski

Stephen B Knuth

Frank Sacca

Kenneth R Core

An integrated cordless telephone and telephone answering device allows a user to selectively replay messages previously recorded on the telephone answering device either through a loudspeaker or through an earpiece, both of which are provided in the cordless handset, as well as locally at the telephone answering device. The loudspeaker is the same loudspeaker that is used when the cordless handset is in a speakerphone mode. When a user wishes to initiate message retrieval through the cordless handset, a PLAY key is pressed which automatically supplies the audio signal to the loudspeaker. If the user then wishes to listen to messages through the earpiece in the cordless handset, a MODE key is pressed which supplies the audio signal to the earpiece. In addition, when the user presses a TALK key, the audio signals from the telephone line are automatically supplied to the earpiece, and finally, when the user presses a SPEAKERPHONE key, the audio signals from the telephone line are automatically supplied to the loudspeaker.

Integrated cordless telephone with telephone answering device and method

A telephone answering device (TAD) includes a remote access mode which is operative responsive to dual tone multi-frequency (DTMF) signals. At least three bandpass filters each receive an input signal from a telephone line interface provided in the TAD. A software controlled sampling section receives outputs from all the bandpass filters for sampling outputs from the bandpass filters, the sampling section including a multiplexer which receives the outputs from all of the bandpass filters, and a peak hold circuit coupled to an output of the multiplexer. An analog-to-digital converter receives an output from the peak hold circuit, and a digital controller receives the output of the analog-to-digital converter for controlling operations of the TAD in a remote access mode responsive to the detected DTMF signals. First and second ones of the bandpass filters have respective center frequencies corresponding to frequencies of respective DTMF signals and a third bandpass filter has a different center frequency. The absence of an output from the third filter confirms that there is no noise or other undesirable signals that would indicate that an incoming signal is not a DTMF signal. At least one of the bandpass filters preferably is a switched capacitor filter having a center frequency which is switchable between at least two different center frequencies. At least the bandpass filters, multiplexer, peak hold circuit and analog-to-digital converter are all included in a single application specific integrated circuit (ASIC).

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Torrance, CA, United States of America

Alex Nirshberg