Each entry represents a CAS variant in media gateway.
Upon the creation of the entry, the CAS variant
specified by ccasVariantFile will be downloaded to
the media gateway. After the file is successfully parsed
by the media gateway, a corresponding entry in
ccasIfExtIncomingLineSignalTable and a corresponding entry
in ccasIfExtOutgoingLineSignalTable will be automatically
created.
When the entry is deleted, the corresponding entry in
ccasIfExtIncomingLineSignalTable and the corresponding entry
in ccasIfExtOutgoingLineSignalTable will be deleted by the
system automatically.