Question : Cannot set up SIP proxy to server

I'm trying to set up a firewall so that we can allow our SIP server to take incoming phone calls.  I've been told to open up ports 5060 - 5070 UDP, and ports 8766 - 35000 TCP / UDP to the back-end server.  The thing is, I just can't get it to work.
I've got a ZyXEL P-660H firewall providing simple no-NAT connectivity from an ADSL line, with no firewalling or anything.  It simply routes traffic from a phone wire to an ethernet cable as far as I'm concerned.  Sat behind that, I've got a Draytek Vigor 2910VG firewall, which provides VoIP facilities.  I don't think I want to use those as such, as I've got a full-blown SIP server in the background, but I'm not sure where to start.  Does anybody have any experience of these firewalls?  Any experts out there who can help?

Answer : Cannot set up SIP proxy to server

The Genesys Voicegenie product is the type of product that has a high price tag to install and probably to get support too. You'll have to ask the maintainers for some help. If that isn't possible, you could consider using a small Asterisk server as a kind of Session Border Controller to interface between the Internet and the private LAN subnet (using two ethernet interfaces), but that solution is probably beyond the scope of what can be covered by a few posts on Experts Exchange.