Byte value shows DS1 frame and code information for the remote
line unit (HiGain only):
bit 0:1 -
0 - frame format is SF.
1 - frame format is ESF.
2 - Frame format is unframed.
3 - no activity.
bit 2:3 -
reserved.
bit 4 -
0 - line code is AMI
1 - line code is B8ZS.
bit 5:7 -
reserved.