As early as the mid-1990s, PC owners could use software from companies such as Newark, NJ-based Net2Phone to make low-cost calls over the Internet using their home or office computers. But until recently, Internet calling has been more of a curiosity than a serious rival to the traditional telephone network, frequently suffering from poor sound quality and spotty connections. With today's faster Internet service and new hardware that can send Internet calls through regular phone handsets, however, Internet phone connections can be better than conventional ones. And that's leading to the first real surge of interest in Internet telephony.

The key to Internet calling is that it's cheap-for both the provider of the service and the consumer. Voice signals are broken into digital bits and shipped over the public network in the same form as e-mail, Web pages, and streaming audio or video; hence the industry term "voice over Internet Protocol," or VoIP. Because it's generally cheaper to send chunks of voice data on random paths through the Internet than to set up a dedicated telephone connection, voice-over-IP companies can charge less. Rates for international calls can be a fifth of those charged by traditional international phone services.