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configuration of VWIC-1MF-E1 (G703) and channelised E1

We are trying to terminate a channelised E1 delivered by British Telecom (BT) on an NTU 8a. BT advise that timeslots 1-24 are active, providing connectivity to a T1 bearer at the other end of the link.

Our Cisco hardware is a Cisco 3660, VWIC-1MFT-1 (G703)hosted in a dual WAN interface card (NM-2W). Connection to the NTU is straight network cable from the VWIC to a cisco Balun adapter cable CAB-ADPT-75-120 which in turn is connected to the bnc coaxial connectors on the NTU.

Router software release is 12.2.6.

In order to test loops to the telco the Controller has had to be set to: framing no-crc4 (crc-4 does not work), line code hdb3, clock source line.

We have created a channel group with Ts 1-24

Our problem is that the serial interface is toggling between up and down. The distant end of the link is a USA T1.

Has anyone had experience making such a configuration work?