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AT Command Set and S-Registers
Table 4-1. AT Command Reference (17 of 18)
AT
Command Description
%A n
Set Auto-reliable Fallback character
In auto-reliable mode (\N3), with auto-reliable fallback
character enabled (\C2), receipt of the fallback character from
the line during the V.42 detection phase will cause the modem
to switch to normal mode. This allows a remote user with a
non-V.42 modem to connect immediately with a V.42 modem.
A space or carriage return (13) is usually chosen for the
fallback character.
n = 0 –127 (ASCII character code). The default is 13.
%C n
MNP 5 Data Compression
This command enables or disables the use of MNP Level 5
data compression. MNP 5 data compression can improve
throughput by as much as 150%.
%C0
%C1
%E n
Auto-retrain Control (V.22bis and V.32bis only)
This command controls whether the modem will automatically
initiate a modem retrain whenever the Received Data signal
quality falls below a threshold that may affect data reliability.
%E0
%E1
%G n
Auto Fall Forward/Fall Back Control (V.32bis only)
This command selects whether the modem will automatically
initiate a change to a higher or lower speed depending on
received signal quality (i.e., Rate Negotiation). The modem
always responds to any rate change initiated by the remote
modem.
%G0
%G1
%Q
Line Signal Quality
This information indicates the quality of the telephone line
signal.
4-18
Issue 1 November 1994
Disables MNP5 data compression.
Enables MNP5 data compression.
Disables auto-retrain.
Enables auto-retrain.
Disables rate negotiation.
Enables rate negotiation.
0 = Good signal quality
1 = Fair signal quality
2 = Poor signal quality
3 = Equalization loss
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