Voice over IP, or VoIP, is an emerging technology that allows you to use your broadband Internet connection to place and receive voice and videophone calls. Internet-based calls are less expensive than traditional calls (sometimes they're even free), and many VoIP-based communication services are compatible with the old-fashioned global phone network, so you can use these new VoIP tools to place calls to and receive them from traditional phone numbers. By adding some desktop VoIP software tools to your Mac, you, too, can take advantage of Internet calling.
We've reviewed four Mac-compatible desktop VoIP applications: Apple's iChat AV 3.1.4, SIPPhone's Gizmo Project 1.3.2, SightSpeed 4.5, and Skype 1.4. We also checked out a unique product called WengoPhone; still in beta for the Mac, this VoIP plug-in for Mozilla Firefox lets you make and receive calls via the browser.
While each program has strengths and weaknesses, they all do basically the same thing: they present you with a buddy list like the one in an instant-messaging (IM) program, and they allow you to communicate by voice (and sometimes video) with the folks in that list. Perhaps the best thing about these VoIP apps is that they're free downloads and aren't shareware, so they won't time out or periodically nag you to register. Since these programs are free, their makers do charge for some premium features.
To get started using VoIP, you'll need a broadband Internet connection (cable or DSL) and a Mac running OS X 10.3 or 10.4 (some of these tools—iChat AV and Skype, for instance—offer additional functions to Tiger users). You'll also need a microphone and a pair of speakers or headphones. Serious desktop VoIP users will opt for headphones or even a headset-microphone to eliminate echo, one of the negative side effects of using freestanding speakers.