Lan Extension Backup Using xDSL

I hope somebody can help me.

We have two sites in the same city and they are connected via a BT

100Mbps LAN Extension service. Both sites use the same IP address range (192.168.0.0/24) and the company prefer to keep it this way.

Is it possible to backup the connection between sites using a secure tunnel over the Internet (xdsl)?

Thanks for any assistance,

Steve Cage