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CHAPTER 9: Configuring Dial Options
Table 9-3 (continued). DBU Options AT Commands for V.34 Card
DBU Options
CMD AT
Description
Error Control
7=AUTO V.42/MNP
\N6
Auto-Reliable V.42 (LAPM) or MNP operation.
Tries to use V.42 (LAPM) error control first,
and MNP error control next. If neither can be
used, then Normal operation is used.
Flow Control
1=DISABLED
\Q0
Flow control disabled
2=XON/XOFF
\Q1
Enables XOn/XOff flow control
3=CTS ONLY
\Q2
Enables CTS flow control from DCE
4=RTS/CTS
\Q3
Enables CTS flow control from DCE and
RTS from DTE
5=UNI XON/XOFF
\Q4
Unidirectional X-ON/X-OFF
Compression
1=DISABLED
%C0
Compression disabled
2=ENABLED
%C1
Compression enabled
9.3.4 DBU O
PTIONS FOR
ISDN C
ARD
S
WITCH
T
YPE
This option selects the type of telco CO switch providing the ISDN service.
There are three options for ISDN switch types:
• AT&T 5ESS
• NT DMS-100
• National ISDN
9.3.5 DBU P
ASSCODE
The dial-backup passcode adds an additional level of security to the CSU/DSU MS
DBU. A passcode of one to ten characters can be programmed into the unit.
When a dial-backup connection is established, the originate unit transmits a pre-
programmed passcode to the answer unit over the dial-backup connection before
the connection is considered valid. The answer unit compares the received
passcode to a pre-programmed passcode. If the passcode matches, the receive unit
sends a Passcode OK message to the originate unit and goes on-line. If the