AT&T MERLIN LEGEND Installation & Maintenance Manual page 87

System Description
AT&T's INFO2 automatic number identification (ANI)
service. Customers who subscribe to this service can identify
an incoming call on an lSDN-PRl line/trunk by either
telephone number or billing number.
Note: The availability of the caller identification information
may be limited by local-serving (caller's) jurisdiction,
availability, or CO equipment.
Dynamic B-channel assignment. An individual B channel
can be removed from service without blocking calls to or from
any other B channels.
Improved toll restriction. The ways that toll restriction can
be bypassed are limited on ISDN-PRI Iines/trunks.
Reliable indication of far-end disconnect.
Improved SMDR reports. Call timing for SMDR reports is
improved since lengths of times recorded are closer to the
actual billed duration.
Framing Format
To identify the DS0 channels, the DS1 signal is segmented into
blocks of 193 bits, called frames. A frame consists of 24 eight-bit
words (one for each channel) plus a framing bit at the beginning
of each frame: 24 words x 8 bits = 192 bits. Thus, a framing bit
appears in every 193rd bit position of the 1.544-Mbps DS1
signal.
Frames repeat at a rate of 8000 per second, with each frame
repeating DS0 channels 1 through 24 sequentially.
Two methods of framing can be used by a 100D module, but the
framing format chosen must match the framing at the far end:
D4 Framing Format. The system is factory set for the most
common framing format, D4 framing. A D4 frame consists of
24 eight-bit time slots and one framing bit. To synchronize the
1-56 DS1 Capabilities