Guidance IP sued AT&T. Guidance, a Spherix-subsidiary, accused AT&T’s positional location systems of infringing a patent related to the location of a transmitting unit relative to fixed receiving locations (5,719,584). Guidance filed its first lawsuit against T-Mobile over the same patent in August 2013.  The patent originated with Harris Corporation. 12/6, Northern District of Texas, 3:13cv04777