MagicJack uses standard SIP, so once you determine your SIP information (username/password/etc), you can use your MagicJack service with any standard VoIP device. http://magicjackhacks.blogspot.com/2007/11/magicjack-sip-info.html
- The easiest way to uncover your MagicJack SIP information is to use Fiddler.