A gateway includes a network interface and an apparatus for detecting predetermined tones The apparatus includes an input to receive a signal transmitted over the network interface, a frequency divider to divide the signal into two different components, each component being associated with a different frequency sub band, wherein each frequency sub band is selected to include a predetermined frequency of a predetermined tone, a frequency discriminator to determine frequencies of tones in the components, and a decision logic block to provide an indication that a first predetermined tone has been detected when a first determined frequency of a first tone in a first component corresponds to a first predetermined frequency of the first tone.