Hi,
Since it is a WMP100 it is 2G only,this is not in itself able to run VPN software itself in Open AT (it can run SSL at a push), technically you will be able to run a VPN if you are using an external IP stack/VPN client but the overall performance is going to be severely restricted by the fact it is 2G only. The latest firmware for these units is R7.47.7 which is a few years old.
Regards
Matt