1. A method of detecting unwanted conversational media session data, said method comprising: calculating two or more progressive similarity scores each with respect to a different instant during a progress of a real-time conversational media session (hereinafter: “CMS”), wherein each of said scores is associated with a similarity between the CMS's media data that was available at the associated instant and a reference data item corresponding to media data of a previous CMS; and evaluating progressive similarity between the real-time CMS and the reference data item based upon the two or more progressive similarity scores.