Method and apparatus for detecting an activation tone

A method for detecting activation tones on a plurality of subscriber lines, comprising:

• providing a plurality of data processors, each of the data processors being associated with one of the subscriber lines;
• detecting one of a plurality of activation tones on a selected subscriber line, the plurality of activation tones including:
• a first activation tone having an active portion and a silent portion, the active and silent portions repeating periodically at a first frequency having a first period;
• and
• a second activation tone having a phase reversal portion repeating at a second frequency having a second period;
• sequencing between the subscriber lines at a predetermined interval, the predetermined interval being based on the first and second periods;
• and
• signaling the data processor associated with the selected subscriber line in response to detecting one of the activation tones.

A line card for detecting activation tones on a plurality of subscriber lines, comprising:

• a plurality of data processors, each of the data processors being associated with one of the subscriber lines;
• and
• means for detecting one of a plurality of activation tones on a selected subscriber line, the plurality of activation tones including:
• a first activation tone having an active portion and a silent portion, the active and silent portions repeating periodically at a first frequency having a first period;
• and
• a second activation tone having a phase reversal portion repeating at a second frequency having a second period;
• means for sequencing between the subscriber lines at a predetermined interval, the predetermined interval being based on the first and second periods;
• and
• means for signaling the data processor associated with the selected subscriber line in response to detecting one of the activation tones.