I'm struggling with the setup of back to back routers over a private circuit between two buildings. The equipment is Cicso 1601's with the T1 DSU WICs installed. To start I have the 4 wires 1-2 and 4-5 run and corssed at the recieving end. I get the green light on the WIC for CD, but have an AL of yellow. The one router the green CD light is flashing. I cannot determine if it is the hardware or the serial interface service module setup that is wrong. Is there an example of what I would set these interfaces up with? Any help would be great!