Samsung Ubigate iBG2016, Руководство по настройке

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Ubigate iBG2016 Configuration Guide/Ed.00
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Digital Trunk T1-CAS Features
T1 Robbed Bit Signaling Concept
On T1 trunks, a frame consists of 24 timeslots, sent every 1/8000 sec.
Figure 6.7 T1 frame and T1 timeslots for CAS signaling
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.
T1 CAS Signalings
CAS stands for Channel Associated Signalling and various types of CAS
signaling are available in the T1 world. The most common forms of CAS
signaling are loopstart, groundstart, and E & M signaling. These protocols
provide information such as the number that was called, and what state the call
is in. They’re limited in what information they can carry, and are slow to set up.
With this kind of signalling, a set of bits is used to replicate opening and
closing the circuit(as if picking up the telephone receiver and pulsing digits on
a rotary phone), or using tone signalling which is passed through on the voice
circuits themselves
T-1
Trunk
23 0 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)
One T-1
Frame
1 22