Your loan also must be held by Fannie or Freddie to use the HARP program but if you haven't looked into it, take a gander here: HARP Program Web Link, it's been extended to 12/2015! And, yes, you'll be able to tell if your loan is held by one of the GSE's right on this website.
It is dependent upon your Loan to Value ratio...yes. But, remember, many underwater homeowners earned a lot of equity in 2013 so your LTV may have changed enough that you can refi through this program!
That's my short reminder and enlightenment for the day!
Go find out if HARP is going to help you!