Patent ID: 8515022

Claim:
A personal emergency response system comprising: a base unit including: a base unit speaker, a base unit microphone, a base unit telephone interface circuit connected with the base unit speaker and the base unit microphone and a telephone line, a base unit controller, an autodialer, a base unit adjustable hybrid cancellation circuit controlled by the base unit controller and connected between the base unit microphone and the base unit telephone interface circuit, the base unit adjustable hybrid cancellation circuit being configured to reduce a base unit speaker adjustment gain when at least one of a first amplitude of a base unit microphone signal is above a first predetermined threshold and a second amplitude of a telephone line signal is below a second predetermined threshold, and a base unit microphone adjustable gain circuit controlled by the base unit controller to adjust the base unit microphone gain, the base unit microphone adjustable gain circuit being configured to amplify output sound to a first preselected level when sound is transmitted out over the telephone line and for muting the base unit microphone when speech is being received on the telephone line; one or more extension units each including: an extension unit speaker, an extension unit microphone, an extension unit telephone interface circuit connected with the extension unit speaker and the extension unit microphone and the telephone line, an extension unit controller without an autodialer, an extension unit adjustable hybrid cancellation circuit controlled by the extension unit controller and connected between the extension unit microphone and the extension unit telephone interface circuit, the extension unit adjustable hybrid cancellation circuit being configured to reduce an extension unit speaker adjustment gain when at least one of a first amplitude of an extension unit microphone signal is above a third predetermined threshold and the second amplitude of the telephone line signal is below a fourth predetermined threshold, and an extension unit microphone adjustable gain circuit controlled by the extension unit controller to adjust the extension unit microphone gain to amplify output sound to a second preselected level when sound is transmitted out over the telephone line and for muting the extension unit microphone when speech is being received on the telephone line; wherein the base unit controller and the extension unit controller are programmed such that in a help mode, the base unit controller and the extension unit controller assume a master-slave relationship.