CrashDive, I think you may have got the wrong end of the stick on this one.
A permanent IP address does not indicate a permanent connection IE Leased line, Frame relay, SMDS, ATM or "nailed up" ISDN.
All "permanent" relates to is a consistent static IP address as opposed to a dynamically assigned one (which could, by its nature, change)
The reasoning behind using a permanent IP address is for the wide area connection and unless someone has physical access to this it can remain secure as the rest can be hidden behind network address translation or its granddaddy PAT.
A VPN only amounts to a secure (?!!) tunnel through any wide area or local connection you care to name, the connection does not have to be permanent so ISDN or other dialer services can be used.
Any service provider you go to would provide you with an IP address for the connection termination. After that the Ethernet (?) connection to your machine could be by either permanent IP's or Dynamically assigned to your host/server via your WAN connection termination equipment or even from the service provider by way of helper services.
If you would like me to expand on this then say so and I'll email you a phone number.
A Leased line will cost you thousands ££ per annum even for 16kbits (assuming you’re in the UK)
Regards.........Bailed.
(Cisco as well as Aviation professional)