e seeing a large number of errors, and you have a short cable, this might be the problem. Short of replacing the interface with a different model, Cisco recommends either reducing the transmit level of the device on the other end of the DS3 cable connected to your router, or installing attenuators on the line. These cards are pretty common, SO watch out for this. Chapter 21: DS3 Channelized DS3 A channelized DS3 can be configured for voice, data, or both. Because the DS3 is channelized, individual T1s can be broken out as either data links or voice links. This is done in the controller configuration for the interface. In this example, I've configured the first 10 T1s in the DS3 to be serial data links. did this by assigning the desired number of DSOs to a channel group. Because my links will all be full Tls, I've assigned all 24 DSOs (referenced as timeslots) to each channel group. However, because this is a channelized DS3, I could separate each T1 further by grouping DSOs together. Each group would get its own channel group number. Here's the controller configuration: controller T3 2/0 framing m23 clock source line t1 1 channel group 1 timeslots 1-24 t1 2 channel-gro 1 timeslots 1-24 t1 3 channel-group 1 timeslots 1-24 t1 4 channel-group 1 timeslots 1-24 t1 5 channel-group 1 timeslots 1-24 t1 6 channel-group 1 timeslots 1-24 t1 7 channel-group 1 timeslots 1-24 t1 8 channel-group 1 timeslots 1-24 t1 9 channel-group 1 timeslots 1-24 t1 10 channel-group 1 timeslots 1-24 t1 1 clock source Line t1 2 clock source Line t1 4 clock source Line t1 6 clock source Line t1 7 clock source Line t1 8 clock source Line t1 9 clock source Line t1 10 clock source Line t1 11 clock source Line t1 12 clock source Line t1 13 clock source Line t1 14 clock source Line t1 15 clock source Line t1 16 clock source Line t1 17 clock source Line t1 18 clock source Line t1 19 clock source Line t1 20 clock source Line t1 21 clock source Line t1 22 clock source Line t1 23 clock source Line t1 24 clock source Line t1 25 clock source Line t1 26 clo