FreePBX Firewall

I am using the new FREEPBX firewall. I’ve put my PBX into my router’s DMZ as per instructions and the firewall is doing it’s job as far as I can tell.

I also have the option of “Source Address Restriction” as I’m using Tomato USB by Shibby.

Would it be advisable to get a list of IP’s for Vitelity and put them into the router so that the DMZ is only available to Vitelity?

I don’t host my own server and don’t have any remote phones that need to access my system, everything is internal.

Or is there a better way of locking things down further?

Be nice and speak slow… I’m still very green at this.