Callertone Innovations [NPE] filed suit against AT&T over two patents related to associating an audio message with an incoming call. Ringback tones provided by AT&T are the accused product. Ringback tones are audio messages selected by a phone subscriber to personalize the ringtone that callers hear when they place a call to the subscriber’s phone number.  This is the first suit filed by Callertone.  The patents-in-suit were issued to Network Directory Sciences (an entity that appears to be related to Mount Hamilton Partners via assignment records) and were assigned to Callertone in February 2011.  10/18, District of Delaware, 1:2011cv00996.