大概在13%，但美國政府的電話都是VOIP

http://arstechnica.com/telecom/news/2010/06/over-20-million-voip-subscribers-in-the-united-states.ars

VoIP users take note—you now command a noticeable share of wireline telephone service in the United States. The Federal Communications Commission reports 21 million subions to Voice over Internet Protocol accounts provided by companies like Vonage, as well as the telcos and cable providers.

These represented 13 percent of the nation's 162 million wired connections as of December 31, 2008. The overwhelming majority were residential. Only one percent of those VoIP lines served businesses.