Method and apparatus for detecting subscriber alerting signal tones and customer premises equipment alerting signal tones to non-echo canceling modems

A method for detecting subscriber alerting signal (SAS) and CAS tones in a non-echo canceling voice band modem, said method comprising:

• utilizing a shaping filter in a transmitting path of said modem to filter signals to be transmitted from said modem;
• utilizing an analog-to-digital converter (ADC) in a receiving path of said modem to convert incoming signals;
• and
• coupling an echo canceler to said shaping filter and said ADC for cancelling echoes in modem signals from said shaping filter and said ADC before sending said modem signals to a SAS tone detector and a CAS tone detector.

A computer program product residing on a computer usable medium for detecting subscriber alerting signal (SAS) and CAS tones in a non-echo canceling voice band modem, said computer prograam product comprising:

• program code means for utilizing a shaping filter in a transmitting path of said modem to filter signals to be transmitted from said modem;
• program code means for utilizing an analog-to-digital converter (ADC) in a receiving path of said modem to convert incoming signals;
• and
• program code means for coupling an echo canceler to said shaping filter and said ADC for cancelling echoes in modem signals from said shaping filter and said ADC before sending said modem signals to a SAS tone detector and a CAS tone detector.