CHANNEL_INFO_ST

vpack
Number of the physical digital trunk.
channel
Number of the physical channel assigned to the channel process. This field will be set to 0 for music channels.
music_channel
The number of a music channel on the pack specified in vpack. This field is used only when channel is set to 0 indicating a music channel. The value of this field must be in the range 1 to MAX_MUSIC_CHANNELS_PER_PACK.