From Consumer Reports:

Consumers tired of paying big bills for traditional landline telephone service are increasingly turning to Internet phone service programs for some financial relief. According to the January issue of Consumer Reports, consumers are saving $20 to $50 or more a month by using VoIP and enjoying many more features and capabilities. But the experts at Consumer Reports note that consumers who use VoIP phone services may also have limited access to emergency 911 services and for this reason, Consumer Reports strongly recommends that consumers keep a basic landline even if they get VoIP for day-to-day use. Despite drawbacks and limitations to VoIP phone service, a nationally-representative Consumer Reports survey of 201 VoIP users shows that more than half were highly satisfied using VoIP in light of costs, service, and problems. A free comparison chart of some of the major VoIP service providers and plans is available at http://www.ConsumerReports.org?source=CR50.

VoIP, or Voice over Internet Protocol, transmits voice calls over the same Internet lines that carry e-mail. Along with lower rates, most VoIP providers also include typical add-on features such as voice mail, caller ID, and call waiting, plus others such as the ability to make local calls using a home number even when thousands of miles away from home. Consumer Reports points out that VoIP requires a broadband connection such as cable or DSL, and the service won't work if the power goes out or the Internet connection is lost.