How can I use my computer for internet phone only?

My internet phone ( magicjack ) requires my computer to be turned on. I do not use my computer though. I keep the monitor turned off.How can I make my computer only run the phone application, and not run any other applications, and use a lot of power ?

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Magic Jack as "a wireless client with a network adapter in a single device which allows a telephone to connect to a network access point for the purpose of establishing Voice over IP." So in that sense, Magic Jack is similar to other Internet Telephony services like Vonage or Skype, which allow you to make phone calls over the Internet.
The unique thing about Magic Jack is that it plugs directly into your computer. In a nutshell, you hook up your existing telephone to one end of the device and the other into your USB port. MagicJack works with Windows XP/Vista and Intel-based Mac computers, you must have a high speed connection, such as DSL, cable or fiber. Your phone works the same for dialing out and receiving calls, no special access codes or prefixes are needed.
You need to turn on your computer.

Then just run your MagicJack application and do not run any other applications. This is why some people are staying away from MJ because it needs a computer to make or receive calls.

What if I remove the router and attach the internet cable direct to my computer?

__________________
Anyone who has never made a mistake has never tried anything new.