The number of Internet-based phone service subscribers in South Korea has topped 10 million in less than six years since the debut of the service, government data showed Monday, amid the continued downturn in traditional landline service. Subscribers of voice over Internet protocol (VoIP) service numbered 10.1 million as of June, the Korea Communications Commission (KCC) said in a statement. The figure marks about 20 percent of South Korea\'s 50 million population.