Centre One has added a second case, this one against Cox Communications (8:19-cv-01832), to the litigation campaign that the plaintiff revived against AT&T in August 2018. The asserted patents belong to a family of seven generally related to voice communications using an interface or gateway system between an IP network, such as a premise-based IP network, and a public switched telephone network (PSTN). Centre One targets voice over IP (VoIP) services that switch calls between PSTN and VoIP networks in this campaign, which began in December 2008 in a case filed against Deltathree, Vonage, and Verizon.