No sound on external extensions


Firstly id like to say hi to the community i am a newbie here and to PBXing.

I have a fresh install of the freePBX distro on a linux virtual machine. But sound is not getting to external extenstions.

Im happy to pay for module and pay for support but id like to see it working and what quality of service it is going to be first.

My Setup:

My HOST server is a windows 2008 server running in a datacenter with 1 or more static IP addresses. For testing purposes i have lowered the firewall and opened all traffic to this.

Im running the freePBX distro on an Oracle virtualbox GUEST machine with NAT giving my freePBX internal IP

The GUEST virtual machine can detect my server has a static IP and sets up NAT and static IP for me when i hit “Auto Configure”

I have forwarded ports 5060 and UDP 10001 - 20000 to the freePBX machine.

My extension (at home) can register with the PBX and says “On hook” it will ring if an incoming call comes in but there is no sound!

In FreePBX “Sip Info” logs it does say my extension is OK (xxx MS) but it states my extension Host is i assume this is why i cant hear sound? Clearly my IP address on my home broadband is NOT as is the IP address from the HOST machine to the PBX Virtual Box.

Can anyone advise me if this setup is ever going to work.l If i buy support are they going to tell me it cannot be done?