We are running a PPTP VPN, when we use the Sierra data cards within NZ we can connect fine to our VPN.

However when roaming in Oz the VPN refuses to connect. I did some port test etc and I can see that in Oz port 1723 is allowed through but what is being blocked is port 47 GRE which is essential to PPTP VPN's..

Since we are behind NAT and getting a 10.x.x.x address, I don't see how this will work without allowing GRE through. Talking to the wireless helpdesk they told us to use a valid Xtra username and password which should give us a real ip address. We tried this, however the username and password were rejected. Wireless helpdesk said it should work, goodbye thankyou...

It is a jetstream login without the .xadsl, it works fine via xtra web mail...

Now I understand with a Voda card we just change the APN to web.vodafone.co.nz and it gives a real IP address so the VPN works fine.

Any suggestions? Apart from giving all these Sierra cards back?
Can anyone confirm using an Xtra username/password to establish the connection is Oz will indeed give you a real ipaddress?