http://www.magicjack.com/If you have a teenager that needs a second or third line at home or even in a situation with roommates or adult children or parents sharing a home, this could be a low cost solution.
Also if you are out of the country think about getting a magicjack to talk to family in the US. Since the company is based in the US then calls inside the US are free. Your voice traffic will route via the Internet to the US then to the persons local phone number. As far as magicjack is concerned you will look like your calling from inside the US.
The company has a robust nationwide network that Borislow says is also a certified CLEC; the company has interconnect agreements with all the larger carriers, meaning it's not about to be shut down like some other value-cost calling operations; and as part of its initial marketing push, MagicJack plans to give away a free phone number.
The business side of MagicJack, as best as we can tell, comes from the subscription plans as well as interconnect fees paid to MagicJack's CLEC partner company (apparently called YMax Communications Corp.) whenever a MagicJack phone number is called. More details — such as additional features embedded into the product, like voicemail, conference calling, and a direct-to-Google search link — will be revealed at the "official" announcement, whenver that is. (At the current leak rate, Borislow might not have much left to tell, other than "some big marketing plan" that he kept to himself Monday.)
Test from various gadget review sites are reporting the voice quality was good. Some reported only the occasional crackle and pop, and no dropped calls. This level of quality and stability is courtesy of magicJack's proprietary network, which maintains a solid, reliable connection that the company claims can't be achieved on traditional VoIP channels. MagicJack has all of the features, voicemail (you can receive messages even when you're offline), caller ID, call waiting, call forwarding, and emergency 911 dialing.
Priced at an incredible $39.95, magicJack comes with a year's worth of service (an annual subscription runs $19.95 after that, with international prepaid packages starting for as little as $5). Although it's designed for use with a single phone line (multiple lines require a magicJack for each) and your PC has to be turned on to use it, the magicJack is a fine way to cut your monthly telephone bill.
Testing results: High voice quality. Most corporate firewalls will block the VOIP ports. There is a problem with automated menus touch tones. When call a company with a menu or if you have to enter a account number it doesn't work so well.