HOLMDEL, N.J. — Verizon Communications Inc. has charged that Internet phone carrier Vonage Holdings Corp. violated patent rights that Verizon has on technology for making phone calls over the Internet. The lawsuit was filed in U.S. District Court in Richmond, Va., on behalf of subsidiaries Verizon Services Corp., of Arlington, Va., and Verizon Laboratories Inc., of Waltham, Mass. Holmdel-based Vonage, which said Monday it had been sued, contested the claim. "Vonage believes that its services have been developed with its own proprietary technology and technology licensed from third parties and intends to vigorously defend the lawsuit," the company said in a statement. Vonage spokesman Mitchell Slepian declined to comment further. Vonage stock dropped more than 9 percent in trading Monday afternoon on the New York Stock Exchange, the latest blow to shares that have lost about half their value since the company went public in late May.