magicJack is a device that plugs into a USB port on the user's computer (or in the case of magicJack Plus, plugs directly into a router) and that has a standard RJ-11 phone jack into which any standard phone can be plugged. This allows the user to make unlimited phone calls to U.S. and Canada. It is a computer peripheral that, in combination with telephony service from the related YMAX Corporation, provides Internet-based telephone service (VoIP) to the United States and Canada. In 2011 the company introduced magicJack Plus, which no longer requires a computer.
Voicemail is stored on the magicJack servers and is delivered via direct telephone access, and email with WAV audio file attachments. Downloadable feature upgrades for the magicJack USB dongle are available from third-party software companies.
The firm's first product, introduced in 2007, is a USB device that has both the software necessary to place Internet-based telephone calls via a customer-supplied high-speed Internet connection and the electronics which allow conventional landline telephones to be plugged directly into the device.
In September 2011 the company introduced magicJack Plus, which does not require the use of a computer after its initial online registration and account set-up procedure. The device connects directly to a modem or router's ethernet port, and has a standard phone jack (which allows a phone to be connected to the device) as well as an AC power adapter that plugs into a standard U.S. electrical outlet.
Excerpted from Wikipedia