Just a little bit of background information for this question.
I have 15 remote sites which needs to have their telephone equipment linked together so calls can be routed other the internet between sites and reduce costs. Each site has an ADSL connection with a draytek 2900 router and has a lan range of 10.0.x.0/255.255.255.0.
We originally tried a mesh topology which was a bit of a knightmare to configure when new sites where brought onboard and also the VPN connections only seemed to stand up for about 10 minutes until they restarted so calls where constantly being dropped of the VPN just work full stop.
We then changed this to a hub and spoke topology and designated one of the sites as a virtual head office to act as the hub. This was a massive improvement and the VPN connections where standing up for days. As the sites started getting busier and more simulatenous calls where routed through the head office hub the calls quality has started getting worse to an unusible point. I assume this is down to the fact that no matter what site is being called the data has to be routed through the head office and on an ADSL connection is just cant keep up with the data flow.
We cant afford to put a leased line into any of the sites as this would negate the cost saving of routing over the internet so I thought I would setup a cloud based windows server 2008 through rackspace and have that as the head office/vpn hub as it would then have the connection we needed.
So to the question (finally) I have enabled remote dialins and setup a test account for one of the sites. The site dials into the Windows VPN fine but I cant seem to be able talk to the phone system on the LAN of the VPN connection. When I had this on just drayteks it was a LAN to LAN connection which worked perfectly. I am hoping this is just a silly routing issue but I have tried all sorts of configurations and just cant get it working.
Please ask for any further information and sorry for the length of the question.