Most voip applications use roughly 300kbs - 500 kbs download and a little less upload...depending on who you are using and quality. I'm sure magic jack is in that range plus it will take up system resources since its a usb connected to your computer.
I'm sure you can find more info here http://www.magicjack.com/1/faq/
EDIT: Found this: A minimum bandwidth UPLOAD speed of 128 kb/s (or kbit/s or kbps) is required.
Obviously, FiOS will no cause any issues with magicjack speedwise...if that is what you are getting to...
Start a new topic or ask questions in the open forum.
