2. The method of claim 1 , further comprising selecting, by the at least one processor, the subset with long call duration.
2. The method of claim 1 , further comprising selecting, by the at least one processor, the subset with long call duration. 4. The method of claim 2 , wherein the extracted patterns include an identification of a reason for call length of the selected subset with long call duration and an indication of which particular topics, events or dialog acts are most likely to result in abnormally long calls.