Operation Manual

ARGUS
A
RGUS 125 27
- Initialization on a PRI access
As soon as Layer 1 is successfully setup, the “L1 Sync” LED will light continuously. The
ARGUS will automatically determine and display, whether or not the PRI access uses
CRC4-monitoring. CRC4 monitoring can be switched on or off manually (see “CRC4 mode”
on page 123.).
The ARGUS will begin to automatically determine the access configuration. After Layer 2 is
setup, the “L2 Rx/Tx” LED will also light.
The ARGUS will, regardless of the mode of operation (TE or NT mode), determine the D-
channel protocol and attempt to setup Layer 3.
During this phase, the ARGUS displays the A bit
of the remote side and the FAS. The protocol can
only be determined when the A bit is not set (+).
FAS (Frame Alignment Signal): Indicates
whether the ARGUS could correctly synchronize
with the incoming 2 Mbit data stream’s
alternating frame identification word or message
word and the, perhaps present, CRC4-
superframe structure.
Afterwards, the ARGUS will start the B-channel test. The ARGUS will check the availability
of all 30 B-channels by placing an outgoing call on each B-channel one after the other. If
the ARGUS can place a call on a B-channel, it will be assumed that the B-channel is
available in both directions; the B-channel test cannot distinguish between alternating and
exclusively "outgoing" B-channels. If the connection is rejected with Cause 44 (see
Appendix B), the B-channel will be assumed to be only available for incoming calls. If the
connection is rejected for any other cause, the B-channel will be identified as unavailable.
In the case of a cause, which indicates that the B-channel is occupied, the connection will
be tried up to two times and, if a connection can still not be setup, it will then be marked as
unavailable.