I'm not really visualizing the box you're talking about, but 1,2,4,5 is the pin out for an RJ 48X. (2,1 = Receive T&R; 5,4 =Transmit T&R)
I never liked using Cat5 for anything over 40' and usually preferred not to use it all for anything but perhaps a patch cord. If it's under 100' you could try it. Do you have a T-1 test set (Sunset, T-Berd etc) to verify that your run is good and not taking any errors?
For a run like this I would recommend 2 runs of shielded Cat 3, with one pair from one cable supplying the Transmit pair and one pair from the other cable supplying the receive.
Sam
