Vonage Holdings stepped closer to putting its legal troubles behind it as it agreed in principle to settle patent infringement claims brought against Vonage by AT&T for $39 million. The announcement follows on the settlement of patent litigation last month with Sprint Nextel and Verizon Communications, which, respectively, will receive $80 million and between $80 million and $120 million from Vonage. (The exact amount of Vonage’s payout to Verizon depends upon the outcome of an upcoming appeals court ruling that relates to two Verizon patents.) Filed late last month with the U.S. District Court in Madison, Wisconsin, AT&T’s complaint concerns a patent, awarded to AT&T in 2002, that enables callers to use standard telephone equipment to make VoIP calls. Although a settlement remains to be finalized, Vonage is proposing to pay AT&T $39 million over the next five years for Vonage’s use of the patent in question. Promising that Vonage will “work diligently” with AT&T to complete the agreement, Vonage Chairman Jeffrey Citron proclaimed that, “with most of the litigation behind us . . . we’re excited to refocus on running our business.”