The U.S. VoIP market has experienced a 16.7 percent annual growth rate over the last five years and generates $15 billion in annual revenue, according to IBISWorld's VoIP in the US report.

A full 65 percent of VoIP users in the United States get their VoIP service through cable companies such as Comcast (Nasdaq: CMCSA), Cox, and Time Warner Cable (NYSE: TWC). "Cable companies able to bundle VoIP service with cable service will fare best in consumer markets in the coming five years, while businesses will slowly but surely turn to VoIP for voice needs," according to the report.

IBISWorld expects the increasing deployment of 4G mobile data networks to fuel continued growth in the VoIP market. In addition, Juniper Research recently predicted that mobile VoIP users would reach 1 billion by 2017.

An increasing portion of VoIP customers are small and medium size businesses and enterprises. T. J. McCue, a contributor to Forbes magazine, estimates that VoIP technology has saved companies "millions of dollars" in phone charges.

Perhaps sensing the increasing popularity of VoIP, Google (Nasdaq: GOOG) announced it is extending its free VoIP calling offering from Gmail in the United States and Canada through 2013.

"Many of you call phones from Gmail to easily connect with friends and family. If you're in the US and Canada, you'll continue to be able to make free domestic calls through 2013. Plus, in most countries, you can still call the rest of the world from Gmail at insanely low rates," wrote Mayur Kamat, Gmail product manager, in a blog.

Source: IBISWorld