Skype

Professional reviewers and users alike love Skype because it allows you to have free PC-to-PC VoIP calls or video calls. One drawback is sound quality that is decent at best, and poor in some reviews. Some experts say Skype isn't VoIP per se, but something different -- peer-to-peer technology that requires a special headset and microphone or a dedicated Skype phone. If you want to call landline phones, you'll need to subscribe to Skype's pay service (about 2 cents per minute or $3 per month for unlimited calls in the U.S. and Canada). Reviews recommend Skype for free international calls to other Skype users, as well as for very inexpensive international calls to landline and cell phones. Skype isn't designed, however, to be the sole telephone for the household, mainly because it can't make 911 calls. Hardware-based VoIP services such as Vonage (*Est. $10 to $35 per month) offer 911 service, and your computer doesn't need to be on to make calls -- but you'll need a backup battery or cell phone in case the electricity goes out. For domestic calls, Google Voice Calls from Gmail (free) service gets good reviews.

ConsumerReports.org ranks 13 VoIP providers, including Skype, in its report on bundled services, and also provides a single-product review of Skype. A more recent but smaller comparison review at SpotCoolStuff.com compares Skype with Vonage, MagicJack and Ooma, as does a review in The New York Times. We found user reviews at DSLReports.com. The comparison review at TopTenReviews.com doesn't document its testing procedures, but provides ample details about Skype features.