Channel number of the DS1/E1 on its parent DS2/E2 or DS3/E3.
Integer (0...28)
Read-only
p.6.1.19.n, where n = the index number of the DS1 interface.
A value of 0 indicates this DS1/E1 does not have a parent DS3/E3.
Note: The NMS SNMP agent always returns 0.