Black Box 32144 Manual page 113

Table 4-3. V.22 bis/V.22/V.21/V.23 Fallback
Mode
V.22 bis
V.22
V.21
V.23
All modes are full duplex.
The operating mode can be
controlled by the user through the
SPEED LIMIT screens on the LCD
in all modes except Hayes mode.
See Chapter 3 for details.
If you want to select 1200/75
bps for both the maximum
and minimum rate, V.22
bis/V.22/V.21/V.23 fallback
must also be selected.
4.3.2 A
UTOMATIC
Both sections below apply to both
dial line and leased line operation.
Rate Renegotiation Procedure (RRP)
If Rate Renegotiation Procedure
(RRP) is enabled, the modem will
automatically fall back or fall
forward to a lower or higher data
rate at any time during data
transmission (without retraining)
in response to changes in signal
quality. Data rate adjustments are
limited to the range of 4800 to
14,400 bps and are also limited by
CHAPTER 4: General Operation and Special Features
Description
2400 bps asynchronous/synchronous
1200 and 600 bps asynchronous/synchronous
300 bps asynchronous
1200/75 bps asynchronous
NOTE
R A
ATE DJUSTMENT
the minimum and maximum rate
settings of the Speed Limit option.
If satisfactory performance cannot
be attained at any of the available
data rates, the modem will initiate a
GSTN cleardown (line disconnect).
If the originate modem attempts to
negotiate a rate that is lower than
the minimum rate setting of the
answer modem, the answer modem
will initiate a GSTN cleardown.
RRP will function only if Speed
Fallback is enabled (factory
default) and if the V.32 Mode
option is set to V.32 bis (factory
default). (Both are Summary Setup
options.)
The factory default setting for
RRP is enabled. To change the RRP
option, refer to Appendix B, Fig. B-
7. Change the Rate Regeneration
Procedure (RRP) parameter shown
in the diagram to 0 (disable) or 1
(enable). (This is the only way the
RRP option can be changed.)
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