what you probably could do is set up a ACL to route all of that traffic out of a specific port in this case the Ethernet port. but if you want to do it a diffrent way just buy another router hook it up to the network and on the original router just set the ACL to not allow any traffic on to the port with the frac t1 unless its coming from or going to your secondary network which would be your DMZ which would keep all of your data separate but as far as doing it with out having the frac t1 with out its own termination i don't know if thats possible because i am almost sure there is no way on the router that you can set it to use only the frac t1 if its all bundled up like that.