I have purchased four Magic Jacks. All four of them have stopped working within the first 6 months.
I bought them for different offices all over the world. Most recently I found that the problem with one of them is the extension cord. The arrogant Magic Jack employee told me that it was my problem because they gave that cord to me for free. They told me I could buy a new one.
This particular cord is less than two months old.
They will not stand behind it because it was "free". I guess if the problem would be the Magic Jack itself, I would have paid for the cord and got the MJ for free.