Xerox WorkCentre Pro 423 Service Manual page 117

2.3.2.4 D Channel Troubleshooting
The D channel is used to originate, terminate, and clear calls. See the D-channel sequence
for the normal procedure of the D channel.
If the network answers a call, the CALLPROC signal is recorded at REMOTE in the D-
channel protocol (ICM trace) data of the Transmission (Call) side. This indicates normal
communication up to the switching system. If the remote terminal answers the call, the
CONN signal is recorded. This starts communication through the B channels.
In D-channel troubleshooting, "reason for disconnection" is analyzed.
element "reason for disconnection" is contained in the DISC, RELCOMP, STATUS, and
PROG signals.
In the ICM trace data of a fax where several communication modules (G4M0, G4M1, G3M0,
G3M1, and other), Layer-3 signals in communication by each module are recorded in the
order of generation. "Call number" is a flag. "Call number" in FIF is analyzed and only the
corresponding communication signals are picked up. "Call number" on the termination side
looks the same in trace data but is actually different because its flag bit is 1. See the
contents of each signal.
Signals used for D-channel communication (Layer-3 network of D channel)
"Type" meaning the information element "message type" is a unique value representing each
signal.
Signal name Meaning of signal
ALERT alerting
CALLPROC call proceeding
CONN connect
CONNACK connect acknowledge
PROG progress
SETUP setup
RES resume
RESACK resume acknowledge
RESREJ resume reject
SUSP suspend
SUSPACK suspend acknowledge
SUSPREJ suspend reject
WorkCentre Pro 423/428
The information
Type Description
01 Notice to origination side when
termination side is alerted
02 Display of start on requested call
setup
07 Notice of acceptance on
termination side
0F Acknowledgement of response
between terminal and network
03 Network notice of
interconnection and call
progress
05 Call setup request
26 Request for resetting suspended
call
2E Reestablishment notice of
suspended call
22 Call reestablishment failure
notice
25 Call suspend request
2D Call suspend completion notice
21 Call suspend failure notice
Signal name Meaning of signal
USERINFO user information
DISC disconnect
REL release
RELCOM release complete
REST restart
RESTACK restart acknowledge
CONCON congestion control
INFO information
NOTIFY notify
STATUS status
STATUSENQ status enqiry
03/02
2-85
Type Description
20 User-set unique information
45 End-to-end connection recovery
request or notice
4D Information channel and call
number release request after
information channel clearing
5A Information channel and call
number release notice
46 Channel or interface initialize
request
4E Initialize completion display
79 User information flow control
7B Additional information to send
6E Call information notice
7D Call status notice from terminal
or network
75 Status display message request
Level 2 Troubleshooting
CHAPTER 2 TROUBLESHOOTING