This read-write Integer32 (0..2147483647) is a bitmap identifying which DS0s on this line are configured as CCS D-channels, with a set bit marking that DS0 as a D-channel, applicable only to lines using CCS signaling. While most applications use just one D-channel per span, this bitmap supports multiple D-channels when an application requires it, giving an admin flexibility for more complex signaling topologies. For instance, an admin setting up a T1 for CCS signaling would set the bit corresponding to timeslot 24 in vismCcsChannels to designate it as the D-channel carrying call control signaling.