You can only have a single DSL modem on a phone circuit. You could in theory move the modem from building to building but it sounds like you would have to have the phone company cross connect the phone lines in their pedestal. If the wire between the buildings is actually yours you might be able to use some of the other technology like ethernet over dsl extenders to make this work. What you do is run the DSL router like normal but then use a special pair of devices that take the ethernet in from the lan port of the router and carry it to the other building using a private form of DSL to another device than then converts it back to ethernet. In effect you are doing the same thing that the phone company does to get the signal from their location to your house. The big issue is you must own the wire, the phone company will not allow you to use their equipment ....they would much rather sell you a second dsl connection.