I am trying to install VPN tunnel through SMPP on my centos server and need help or some tutorial which shows how to do it.
You want to implement a VPN over SMS - not the other way around?
If so, short of implementing the IP protocol over SMS I can't really see a good way to make this work.
(Yeah - not possible in any reasonable way as far as I can tell. Ignoring everyhing else, what Lucas said about latency would be a killer. your connections would be timing out constantly.)