ONT ID.
Parameters hwFrameIndex and hwSlotIndex are obligatory, hwOntIndex and hwPortIndex are optional
(the setting -1 indicates that the parameter is optional).
For example, to set the information of all ONTs connected to a specified port returned,
you can set hwOntIndex to -1; to set the information about the status of all ONTs
connected to all ports of a specified slot returned, you can set hwPortIndex and hwOntIndex to -1