Method and apparatus for transmitting signaling tones over a packet switched network

Abstract

As part of a system and method for transmitting a signaling tone over a packet switched data (or other communication) network, an audio encoder may have a speech encoding unit and a tone distorter. The tone distorter may distort one or more components of a signaling tone within an audio signal and the speech encoding unit may encode speech and the distorted signaling tone within the audio signal. A control signal may be sent to a tone generator to reproduce the distorted tone.

What is claimed:  
     
         1 . A method comprising: 
 detecting within an audio signal a frequency component correlated to a signaling tone and distorting the tone within the audio signal.    
     
     
         2 . The method according to  claim 1 , wherein said distorting comprises shifting a frequency component correlated to the tone.  
     
     
         3 . The method according to  claim 1 , wherein said distorting comprises changing a magnitude of a frequency component correlated to the tone.  
     
     
         4 . The method according to  claim 1 , wherein said distorting comprises camouflaging a frequency component correlated to the tone.  
     
     
         5 . The method according to  claim 1 , wherein the tone within the audio signal is distorted by changing one or more levels of one or more of its frequency components.  
     
     
         6 . The method according to  claim 1 , wherein the tone within the audio signal is distorted by changing the level of frequency components near the frequency component correlated to the tone.  
     
     
         7 . The method according to  claim 1 , further comprising transmitting the audio signal with the distorted tone to its destination.  
     
     
         8 . The method according to  claim 7 , fiber comprising encoding the audio signal prior to transmitting the signal to its destination.  
     
     
         9 . The method according to  claim 8 , further comprising detecting a tone within the audio signal and transmitting to a tone generator a control signal instructing the generator to generate the detected tone.  
     
     
         10 . A tone transmission apparatus comprising a frequency estimator adapted to detect in an audio signal a frequency component correlated to a tone, and a tone distorter adapted to modify one or more frequency components associated with the tone while minimally distorting the speech in the audio signal.  
     
     
         11 . The apparatus according to  claim 10 , wherein the tone distorter is selected from the group consisting of a twist distorter, a frequency modulation distorter, a frequency shift distorter, and a power concentration distorter.  
     
     
         12 . The tone transmission apparatus according to  claim 11 , further comprising an encoder adapted to convert the audio signal into one or more data packets.  
     
     
         13 . The tone transmission apparatus according to  claim 12 , further comprising a tone detection unit adapted to detect a tone in the audio signal and to produce a control signal instructing a tone generator to produce the detected tone.  
     
     
         14 . A transmission system comprising; 
 a tone transmission apparatus comprising a frequency detector adapted to detect in an audio signal a frequency component correlated to a tone, and a tone distorter adapted to modify one or more frequency components associated with the tone while minimally distorting the speech in the audio signal; and    an encoder adapted to encode and transmit the audio signal over a data communications network.    
     
     
         15 . The system according to  claim 14  wherein the communications is selected from the group consisting of an ATM network, TCP protocol, an I.P. network, a UDP protocol, and an RTP protocol.  
     
     
         16 . A method comprising; 
 detecting within an audio signal a frequency component correlated to a signaling tone; altering a frequency component associated with the tone such that speech within the audio signal is minimally distorted; and encoding the audio signal with the altered frequency-component.    
     
     
         17 . The method according to  claim 16 , further comprising detecting the tone and sending a control signal to a tone generator.  
     
     
         18 . A tone transmission apparatus comprising a frequency detector adapted to detect in an audio signal a frequency component correlated to a tone; a tone distorter adapted to modify one or more frequency components associated with the tone; an encoder adapted to encode the audio signal with the distorted tone; and a tone detector adapted to detect the tone and to produce a control signal instructing a tone generator to produce the tone.  
     
     
         19 . The tone transmission apparatus according to  claim 18 , wherein the tone distorter only minimally distorts speech within the audio signal.