My Magicjack Blocks Calls To Previously Available Numbers. Csr Wasn't Helpful.

I contact MagicJack twice now about a problem that just started at the beginning of this year. I can no longer call ANY numbers to Inland Cellular customers, eventhough I previously could (I have had MJ for over a year!). My son has Inland Cellular and I haven't been able to call him with my MJ phone, all I get is a message saying "the call cannot be completed as dialed, please check the number and try again". There is nothing wrong with the number, I can call it from my cell phone just fine. The first time I talked to MJ Live Chat, the rep told me to contact the other carrier, that they are blocking MagicJack. I have talked to Inland Cellular and the representative had me try a few things and finally said there is nothing he can do, it's not on their end. The problem is clearly with MagicJack but their customer support can't come up with a solution. One of their techies talked me through a few things to try and solve the problem, all it resulted in was to turn all my computer's protection off, like the Windows firewall and open more ports. This leaves my computer more vulnerable to attacks and it shouldn't be necessary. I hadn't changed anything from the time I was still able to call those numbers to the time when I no longer could (Jan. 1st 2011). I'm at a loss and don't know what else I can try. I would like this problem fixed. I actually ended up getting a cell phone so I am still able to talk to my son who lives several states away.