I have a wierd issue. I have one 1700 series router with a T1 wick and another 3800 series router with several T1 wick. When I connect the 1700 to the 3800 using a t1 roll over cable the serial interfaces comes up then going back down repeatedly. I tried also connecting a 2600 to the 3800 series router with the same results. I keep getting CRC errors, input, and frame errors on the connected interfaces. We connected a hard loop to the 1700 and 3800 T1 wick cards and everything is working fine. What is wierd is when I connect the 1700 series router and 2600 series router together with a T1 roll over cable, they work without issues and the interface is stable. My question is why would connected each of these routers to the 3800 produce bad results. We have other wick cards on the 3800 that are connecting to other routers without problems. I even tried a seperate interface on the 3800 with the same problem. I have included my router configurations.