No, if you are going directly into a csu/dsu it needs to be pinned out as ealrier stated. (1245) Does NOT cross over. By the questions answered, I am assuming that you are extending the circuit from the Smart-Jack? If this is the cae you can either put a mod end on the far side or you could put an rj31x. If the rj31x has nothing pluged into it, this will shrt the jack and send loop back to the LEC. (nice for testing purposes.)