This field is set to a unique channel number within an APS
group. The value 0 indicates the null channel. The values
1-14 define a working channel. If the SONET LTE is not part
of an APS group this value is set to -1.
When an instance of cApsChanConfigIfIndex is set equal
to an instance of cApsMapIfIndex, cApsMapChanNumber
is set equal to the corresponding value of
cApsChanConfigNumber.
If the cApsMapIfIndex ceases to be equal to an instance
of cApsChanConfigIfIndex, either because of a change in
the value of cApsChanConfigIfIndex, or because of row
deletion in the CApsChanConfigTable, cApsMapChanNumber
is set to -1.