Telephone annunciator

Abstract

A telephone annunciator is disclosed which includes a voice ROM with a prerecorded message which is played back in response to a call received from an unwanted caller. A line current modulator is coupled with the voice ROM and the telephone line. A DTMF tone decoder circuit is coupled with the telephone line for decoding at least one DTMF code signal for producing a trigger signal. An on/off control circuit is responsive to the trigger signal for turning on the voice ROM whereby the telephone line current is modulated by the modulator in accordance with the audio signal from the voice ROM. A start-up power supply includes a storage capacitor and stores a charge in response to a ring signal on the telephone line. A main power supply is connected with the telephone line to receive power therefrom when an off-hook signal is detected.

1 . A method of operating an annunciator connected to a telephone line, comprising the steps of: 
 (a) receiving a ring signal indicating an incoming call,    (b) monitoring the telephone line to detect an off-hook condition of another device connected to the telephone line, and thereafter    (c) monitoring the telephone line for a predetermined DTMF signal and, in response to detecting the predetermined DTMF signal, playing a pre-recorded message over the telephone line.    
   
   
       2 . The method of  claim 1 , wherein step (a) further comprises switching the annunciator from a dormant state to an active state upon receiving the ring signal.  
   
   
       3 . The method of  claim 1 , wherein step (b) further comprises monitoring the telephone line for the off-hook condition using an off-hook detector that is powered by the ring signal.  
   
   
       4 . The method of  claim 1 , wherein step (c) further comprises switching the annunciator from an on-hook condition to an off-hook condition following detection of the predetermined DTMF signal, then playing the pre-recorded message, and thereafter switching the annunciator back to the on-hook condition.  
   
   
       5 . The method of  claim 1 , wherein, after detecting the predetermined DTMF signal, the method further comprises the step of (d) monitoring the telephone line for a second DTMF signal and stopping playback of the pre-recorded message upon receiving the second DTMF signal.  
   
   
       6 . An annunicator for use with a telephone set having a keypad thereon and which is connected with a telephone line, said annunicator comprising: 
 a pair of terminals for connection of the annunicator with the telephone line;    a ring detector coupled to said terminals and comprising a first electrical circuit that receives incoming ring signals from the telephone line;    an off-hook detector coupled to said terminals and comprising a second electrical circuit that detects an off-hook condition on the telephone line following receipt of one of the incoming ring signals;    a DTMF signal detector coupled to said terminals and comprising a third electrical circuit that detects a predetermined DTMF signal on the telephone line; and    a voice memory having an input coupled to said DTMF signal detector to receive a signal following detection of the predetermined DTMF signal by said DTMF signal detector, and said voice memory also having an output coupled to the terminals to provide a pre-recorded message over the telephone line;    said annunciator being operable following receipt of an incoming ring signal and subsequent detection of the telephone set going off-hook to thereafter monitor for the predetermined DTMF signal and, in response to receipt of the predetermined DTMF signal, to play the pre-recorded message over the telephone line via the terminals.    
   
   
       7 . An annunicator as defined in  claim 6 , wherein said voice memory is a read only memory.  
   
   
       8 . An annunicator as defined in  claim 6 , wherein the annunciator comprises a housing having at least one telephone jack connected to the pair of terminals.  
   
   
       9 . An annunicator as defined in  claim 8 , wherein said telephone jack(s) are the only electrical connectors on said housing.  
   
   
       10 . An annunicator as defined in  claim 6 , wherein said annunciator includes a line current modulator connected between said voice memory and at least one of said terminals.  
   
   
       11 . An annunicator as defined in  claim 6 , wherein said annunciator includes an energy storage device that provides power to operate said annunciator, and wherein said ring detector is connected to said energy storage device to store energy from the ring signal in said energy storage device.