Method and apparatus for detecting one or more predetermined tones transmitted over a communication network

An apparatus for detecting one or more predetermined tones transmitted over a communication network, each predetermined tone having a predetermined frequency, the apparatus comprising:

• a data memory for storing data including the predetermined frequency of each of the one or more predetermined tones;
• an input for receiving a signal transmitted over the communication network;
• a frequency divider for dividing the received signal into at least two frequency sub bands so as to provide at least two components of the received signal in different frequency sub bands, the different frequency sub bands being selected based on the predetermined frequencies of the one or more predetermined tones;
• at least two adjustment blocks for adjusting the power of the at least two components of the received signal to a predetermined level and for providing power level information for the at least two components and for determining a power level of the one or more predetermined tones;
• a frequency discriminator for determining a frequency of each tone in the at least two components;
• and
• a decision logic block for providing an indication that a predetermined tone has been detected when the determined frequency of a tone in a component corresponds to the predetermined frequency of one of the one or more predetermined tones.

A method for detecting one or more predetermined tones transmitted over a communication network, each predetermined tone having a predetermined frequency, comprising:

• receiving a signal transmitted over the communication network;
• selecting at least two frequency sub bands, the selecting further comprising:
• identifying the one or more predetermined tones to be detected;
• mapping the identified tones onto a frequency spectrum;
• classifying the identified tones according to when the tones are expected to be received;
• and
• dividing the frequency spectrum into at least two different frequency sub bands based on the results of the mapping and classifying steps such that there are no two tones having frequencies in the same frequency sub band and which are expected to be received at the same time;
• dividing the received signal into at least two frequency sub bands so as to provide at least two components of the received signal in different frequency sub bands, the different frequency sub bands being selected based on the predetermined frequencies of the one or more predetermined tones;
• and
• determining a frequency of each tone in the at least two components and providing an indication that a predetermined tone has been detected when the determined frequency of a tone in a component corresponds to the predetermined frequency of one of the one or more predetermined tones.