2250 Console wiring

I have a 2250 console down . It is wired to a 4 pair cable and apparrently has worked for several years like this.I have expeirence using 25 pairs and x-connecting 5 consecutive tns to the 25 pair.This particular console has apparrently worked for some time as is.This one has 4 tns connected to it. All Nortel documentation states that 5 consecutive pairs are required. This one has the first 2 tns unit 0,1 and 3,4 as power.Unit 2 is a 3903. Old console re acts the same connected in equip.There is another console on site that appears to work that is wired the same. Customer is reluctant to allow only other console to be swapped as a test. Anyone with any help is greatly appreciated. Thanks in advance. Al