Have you ever had problems when connecting E1 circuit with regular Ethernet straight-through cable (4 twisted pairs instead of 2)?
The router is at a remote location and I cannot change the cable.
Router type: cisco 2800.
E1 controller is up; serial is up, line protocol is down.
I believe the problem is not in the cable but I checked the configuration and there is no issue as well.
1. Alway use properly wired and twisted T1 cable using T1 pinout.. DO NOT USE ETHERNET CABLE.
2. this said, problem can be in the circuit and not in the cable. Send "show controllers E1" and "show interface serial".
Note: even if the SP swears the circuit is working, that is oftent NOT the case.