Digital Trunk T1-Cas Features - Samsung Ubigate iBG3026 Configuration Manual

9.
Metering
determines if it would create metering pulse for outgoing call.
10.
Request category
DNIS digits to be collected before requesting line category.
When it works as R2 calling side, is used to send call priority defined in R2
to the receiver.
11.
Unused ABCD
Specifies unused ABCD bit values.

Digital Trunk T1-CAS Features

T1 Robbed Bit Signaling Concept
On T1 trunks, a frame consists of 24 timeslots, sent every 1/8000 sec.
On T1 trunks using a CAS protocol, the signaling information for each
channel is transmitted using a method called robbed-bit signaling.
The information for each channel consists of a set of bits(called the ABCD
bits). Whenever a channel's state changes, the ABCD bit pattern for that
channel changes to convey the signaling bits. Signaling information is carried
on a T1 trunk by two signaling bits, an A-bit and a B-bit.
The biggest disadvantage of CAS signaling is its use of user bandwidth in
order to perform signaling functions.
The most common forms of CAS signaling are loopstart, groundstart, Equal
Access North American(EANA), and E & M.
© SAMSUNG Electronics Co., Ltd.
22 23 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1
T-1 timeslot
(8 bits of data)
Figure 31.7 T1 frame and T1 timeslots for CAS signaling
Ubigate iBG3026 Configuration Guide/Ed.00
One T-1
Frame
T-1
Trunk
511