I'm pretty sure you need to have the 2nd pair of your phone jack wired to a dial tone that you want to use for your device. You also have 2 single line ports on your KSU, these are ports 148 & 149. So the 2nd pair of your jack could also be interfaced to one of them, and then program that extension to have incomming and/or outgoing access to a line pool.
We all need a little help once in awhile. Tony the Phoneman..