As major telecommunications carriers begin to roll out Voice over Internet Protocol (VoIP) service offerings to give themselves a competitive edge, residential VoIP has clearly come into its own in the U.S., fueled in part by consumers looking to add value to their telephony service, according to market researchers at IDC.

As a result, the Framingham, Mass.-based firm expects the number of U.S. subscribers for residential VoIP services to grow from 3 million this year to 27 million by the end of 2009.

Although it has been slow to develop in the U.S. and elsewhere, VoIP is finally beginning to show its potential in the consumer market with much of the recent success the result of marketing VoIP services on the basis of price, IDC believes.

However, carriers need to educate residential users on the features and functions of VoIP service to avoid a pricing war as well as add integrated applications and convergence in the years ahead, the firm added.

“VoIP must prove that it is more than just a cheap replacement for [plain old telephone] service,” said William Stofega, senior analyst for IDC’s VoIP services research program, in a statement. “To do this, carriers will need to offer services that are compelling and affordable.

“The winners will use the flexibility of IP to design services that differentiate themselves from their competitors,” he continued. “However, it is important to remember that the market for VoIP services is still in the very early stages of development and carriers and equipment vendors need to plan for a marathon."

Finally, although the market is already crowded with traditional and next-generation carriers, IDC believes that even more service providers, including cable multiple system operators, will launch consumer VoIP products and services this year.