This object represents the total number of Voice Interfaces
within this LIF.
When users associate/disassociate a Voice Interface with
a LIF by giving a non-zero/zero value of
ccasVoiceCfgLifNumber for the DS0 group in
ccasVoiceExtCfgTable, the value of this object will be
incremented/decremented accordingly.
The value zero means there is no Voice Interface associated
with the LIF.