Callertone Innovations [NPE] filed suit against Cricket Communications and Leap Wireless, alleging that defendants’ ring-back tones infringe two patents related to associating an audio message with an incoming call.  Ring-back 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.  Callertone has filed ten prior suits since October 22, 2011 against Alltel, AT&T, Boost Mobile, ClearSky Mobile, LiveWire Mobile, MetroPCS, Sprint Nextel, T-Mobile, United States Cellular, Verizon, Virgin Mobile, and Zed.  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. 11/7, District of Delaware, 1:2011cv01099.