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Technical Configuration (T1/E1) MultiVOIP User Guide
156
T1 Parameter Definitions (cont’d)
Field Name Values Description
CAS Protocol E&M Immed Strt
E&M Wink Start
E&M Wink with
dial tone
FXO Ground Strt
FXO Loop Start
FXS Ground Strt
FXS Loop Start
Channel Associated Signaling
(CAS) is a method of
incorporating telephony
signaling info into a T1
voice/data stream. In CAS, the
signaling bits (the A, B, C, and
D bits) are multiplexed into the
signal stream of each T1
channel. (By contrast, in
Common Channel Signaling
(CCS), one channel handles
signaling for all other channels.)
Each CAS protocol defines the
states of the signaling bits
during the various stages of a
call (IDLE, SEIZED, ANSWER,
RING-ON, RING-OFF).
The CAS protocol code allows
the VOIP to interact properly
with the PBX or central-office
switch that it serves. The need
to download CAS protocols
arises for only a small minority
of VOIP users, and only when
PBX/switch is found to be
incompatible with standard
protocols.
Match this parameter to the
setting of PBX or central-office
switch.