Site A - 2800 as VPNServer PPTP
10.1.1.1 is router
10.1.1.x subnet
IPPBX at 10.1.1.200

Site B - 2710 as VPN client PPTP
10.1.4.1 is router
10.1.4.x is subnet

VPN working all correctly, in that if terminal at Site B say 10.1.4.100 wishes to access 10.1.1.100 at site A it can, and it just routes the traffic over through the VPN. All web traffic is local to the WAN connection.

Issue lies in where the SIP phones at Site B with IP of 10.1.4.50 can reach and register the IPPBX the Site A at 10.1.1.200 and calls can be made, but it seems like the VPN reporting the incorrect IP addresses so inturn some of the SIP packets dont know how to get back to the phone and hence terminating the call.

Calls from Site A --> Site B works fine
Calls from Site B --> Site A works but then drops off (Doesnt receive a SIP ACK)
Calls from Site B --> Site B works but then drops off (Doesnt receive a SIP ACK)

We are going to replace the 2800 with two 2710 on both ends as we are also having some other issues with the 2800 doing odd things sometimes forwarding, sometimes not. Other than that can anyone see any issues with the above config and setup??

Assistance much appreciated as we have been working on this issue for the last 2 months with no resolution in site

TEX