Data and General Commands

Every command except A/, +++, and A> must begin with the AT prefix and be executed by pressing ENTER.

Example: ATDL <ENTER> dials the last number called.

Command Function Default Options
+++ Escapes to online-command mode. Does not require the AT prefix or a carriage return. None. None.
$ Displays help for basic commands. None. None.
A Manual Answer. Goes off hook in answer mode. Pressing any key before the connection is complete aborts the operation. None. None.
A/ Re-executes the last issued command. Used mainly to redial. Does not require the AT prefix or a carriage return. None. None.
A> Re-executes the last issued command continuously until the user intervenes or the command is executed forever. Does not require the AT prefix or a carriage return. None. None.
Bn Set handshaking options. B1 when the modem is at 1200 bps.

B16 when the modem is at 300 bps.
B0 Selects CCITT V.22 mode when the modem is a 1200 bps.
B1 Selects Bell 212A when the modem is at 1200 bps. Use only if the modem is not required to answer V.34-type calls.
B2, B3 Deselects V.23 reverse channel.
B15 Selects V.21 when the modem is at 300 bps.
B16 Selects Bell 103J when the modem is at 300 bps.
Dn Dials the specified phone number. After ENTER is pressed, pressing any key before the connection is complete aborts the operation. The default dialling method is tone (ATDT). None. The maximum length of a dial string is 60 characters.
D0–D9 Numeric digits.
D#D* Extended touch-tone pad tones.
DL Dials the last phone number dialled.
DL? Displays last phone number dialled.
DP Pulse (rotary) dial.
DT Tone (DTMF) dial
DW Waits for second dial tone (X2 or X4); linked to S6 register.
D! (Exclamation point) Flashes the switch hook.
D, (Comma) Pauses. Linked to S8 register.
D/ (Slash) Delays for 125 ms. before proceeding with dial string.
D; (Semicolon) Returns to Command mode after dialling.
D@ Dials, waits for quiet answer, and continues (X3 or higher).
D" (Quotation mark) Dials with alphabetic letters between quotes converted to numbers.
D^ (Circumflex) Disables data calling tone transmission.
DS=n Dials the phone number string stored in NVRAM at position n. Phone numbers are stored with the &Zn=s command. None. 0–2
En Sets local echo. E1 E0 Modem does not display keyboard commands.
E1 Modem displays keyboard commands.
H Controls hook functions. H0 H0 Modem goes on-hook.
H1 Modem goes off-hook.
In Displays the information associated with n. None. I0 Four-digit product code.
I1 Results of ROM checksum.
I2 Results of RAM checksum.
I3 Product type.
I4 Current modem settings.
I5 Nonvolatile memory (NVRAM) settings.
I6 Link diagnostics.
I7 Product configuration.
I9 Plug and Play information.
I11 Extended link diagnostics.
I92 V.92 settings.
Ln Controls speaker volume.
Note:Modem does not have a speaker.
Command is included for compatibility.
L1 L0 Low.
L1 Low.
L2 Medium.
L3 High.
Mn Operates speaker. M1 M0 Speaker always OFF.
M1 Speaker ON until CONNECT.
M2 Speaker always ON.
M3 Speaker ON after dial, until CONNECT.
N Controls modulation handshake N1 0 When originating or answering, this is for handshake only at the communication standard specified by register S37 and the B<value> command.
1 When originating or answering, this is for handshake only at the communication standard specified by register S37 and the B<value> command. During handshake, may fall back to a lower speed.
On Returns online. None. O0 Returns online from command mode.
O1 Returns online and retrains.
P Sets pulse dialling (rotary dialling). None. None.
All subsequent D<dial_string> commands use pulse dialling until either the T command or a tone dial modifier is received by the modem.
The modem uses tone dialling by default.
Qn Displays/suppresses result codes. Q0 Q0 Displays result codes.
Q1 Quiet mode; does not display result codes.
Sr=n Sets S-register r to the value n. For register values, see S-Registers. None. None.
T Sets DTMF tone dialling. None. None. The modem uses tone dialling by default.
Vn Displays verbal/numeric result codes. V1 V0 Displays numeric result codes.
V1 Displays verbal result codes.
Wn Enables tone detection options. W2 W0 CONNECT result code reports DTE receive speed. Disables protocol result codes.
W1 CONNECT result code reports DTE receive speed. Enables protocol result codes.
W2 CONNECT result code reports DCE receive speed. Enables protocol result codes.
Xn Sets result codes displayed. X4 This command enables tone detection options used in the dialling process. As each function is chosen, the modemís result codes are also affected. Therefore, this command is frequently used to control the modemís responses. The primary function of this command is to control call response capabilities.

Commands
Command Extended Result Codes Dial Tone Detect Busy Tone Detect
X0 Disabled Disabled Disabled
X1 Enabled Disabled Disabled
X2 Enabled Enabled Disabled
X3 Enabled Disabled Enabled
X4 Enabled Enabled Enabled
X5, X6 Enabled Enabled Enabled
X7 Disabled Enabled Enabled

Option Description
Function Enabled Disabled
Ext Result Codes Displays basic result codes, connect messages with data rate, and an indication of the modem's error correction and data compression operations. Displays the basic result codes.
Dial Tone Detect Dials upon detection of a dial tone and disconnects the call if the dial tone is not detected within 10 seconds. Dials a call regardless of whether the modem detects a dial tone. Register S6 contains the dial delay.
Busy Tone Detect Monitors for busy tones. Ignores all busy tones.

Option Result Codes
Command Result Codes
X0 • OK • Ring • Error
• Connect • No Carrier  
X1 • OK • Ring • Error
• Connect <Rate> • No Carrier  
X2 • OK • Ring • Error
• Connect <Rate> • No Carrier • No dial tone
X3 • OK • Ring • Error
• Connect <Rate> • No Carrier • Busy
• Blacklisted    
X4 • OK • Ring • Error
• Connect <Rate> • No Carrier • Busy
• Blacklisted • Delayed • No dial tone
• Call Waiting detected    
X5, X6 • OK • Ring • Error
• Connect <Rate> • No Carrier • Busy
• Blacklisted • Delayed • No dial tone
• Call Waiting detected    
X7 • OK • Ring • Error
• Connect • No Carrier  
Yn Selects reset default configuration. Y0 Y0 Selects stored profile (&W).
Y1 Selects stored profile (&W).
Y2 Selects factory configuration 0 (&F0).
Y3 Selects factory configuration 1 (&F1).
Y4 Selects factory configuration 2 (&F2).
Zn Resets modem. Z0 Z0 Resets the modem to NVRAM profile selected by Y command.
Z1 Resets the modem to the stored profile (&W).
Z2 Resets the modem to the stored profile (&W).
Z3 Resets the modem to factory default profile 0 (&F0).
Z4 Resets the modem to factory default profile 1 (&F1).
Z5 Resets the modem to factory default profile 2 (&F2).
#CID=n Controls Caller ID. None. #CID=0 Disables Caller ID.
#CID=1 Enables formatted Caller ID.
#CID=2 Enables unformatted Caller ID.
#UD Displays Unimodem Diagnostics. None. None.
%B Displays numbers in blacklist. (Country selection must support blacklist.) None. None.
%En Controls Fallback/Fallforward. %E2 %E0 Fallback/Fallforward disabled.
%E1 Fallback enabled, Fallforward disabled.
%E2 Fallback/Fallforward enabled.
&An Enables/disables added result code subsets (see Xn). &A3 &A0 ARQ result codes disabled.
&A1 ARQ result codes enabled.
&A2 V.xx modulation indicator added.
&A3 Protocol indicators added: LAPM/MNP/NONE (error control) and V42bis/MNP5 (data compression).
&Bn Manages the modem's serial port rate. &B1 &B0 Serial DTE rate is variable, follows connection rate.
&B1 Fixed DTE rate.
&Cn Controls Carrier Detect (CD) signal. &C1 &C0 CD override.
&C1 Normal CD operation.
&Dn Controls Data Terminal Ready (DTR) operations. &D2 &D0 Data Terminal Ready (DTR) override.
&D1 DTR toggle causes online Command mode.
&D2 Normal DTR operation.
&D3 Resets on receipt of DTR.
&Fn Resets the modem and loads a read-only (non-programmable) factory configuration. None. &F0 Loads a generic template.
&F1 Loads the hardware flow control template.
&F2 Loads the software flow control template.
&Gn Sets Guard Tone. &G0 &G0 No guard tone, U.S. and Canada.
&G1 550 Hz guard tone; requires B0 setting.
&G2 1800 Hz guard tone; requires B0 setting.
&Hn Sets Transmit Data (TD) flow control. &H1 &H0 Flow control disabled.
&H1 Hardware flow control, Clear to Send (CTS).
&H2 Software flow control, XON/XOFF.
&Kn Enables/disables data compression. &K1 &K0 Data compression disabled.
&K1 Auto enable/disable.
&Mn Sets Error Control (ARQ) for connections at 1200 bps and higher. &M4 &M0 Normal mode, error control disabled.
&M4 Auto Normal/ARQ.
&M5 ARQ required for connection.
&Nn Sets S registers to attempt forced speed. &N0
n Rate S28 S37 S38
0 Auto rate 1 0 1
1 300 V.21/B103 0 3 0
2 1200 V.22 0 5 0
3 2400 V.22bis 0 6 0
4 4800 V.32 0 7 0
5 7200 V.32 0 8 0
6 9600 V.32 0 9 0
7 12000 V.32bis 0 10 0
8 14400 V.32bis 0 11 0
9 16800 V.32ter 0 12 0
10 19200 V.32ter 0 13 0
11 21600 V.34 1 14 0
12 24000 V.34 1 15 0
13 26400 V.34 1 16 0
14 28800 V.34 1 17 0
15 31200 V.34+ 1 18 0
16 33600 V.34+ 1 19 0
17 28000 V.90 1 0 2
18 29333 V.90 1 0 3
19 30666 V.90 1 0 4
20 32000 V.90 1 0 5
21 33333 V.90 1 0 6
22 34666 V.90 1 0 7
23 37333 V.90 1 0 8
24 37333 V.90 1 0 9
25 38666 V.90 1 0 10
26 40000 V.90 1 0 11
27 41333 V.90 1 0 12
28 42666 V.90 1 0 13
29 44000 V.90 1 0 14
30 45333 V.90 1 0 15
31 46666 V.90 1 0 16
32 48000 V.90 1 0 17
33 49333 V.90 1 0 18
34 50666 V.90 1 0 19
35 52000 V.90 1 0 20
36 53333 V.90 1 0 21
37 54666 V.90 1 0 22
38 56000 V.90 1 0 23
&Pn Sets the make-to-break ratio. &P1 &P0 U.S. ratio: 39%–61% at 10 pulses per second
&P1 UK ratio: 39%–61% at 10 pulses per second
&P2 UK ratio: 39%–61% at 20 pulses per second (Japan)
&Sn Sets the Data Set Ready (DSR) option. &S0 &S0 DSR override. DSR is always on.
&S1 DSR comes on after establishing a connection and goes off when the connection ends.
&Tn Sets test modes. None. &T0 Ends testing.
&T1 Local Analogue Loopback (LAL).
&T3 Local Digital Loopback (LDL).
&Wn Stores current configuration in NVRAM template. None. &W0
&Yn Sets break handling. &Y1 &Y0 Destructive, but doesn't send break.
&Y1 Destructive, expedited.
&Y2 Nondestructive, expedited.
&Y3 Nondestructive, unexpedited.
&Zn=s Stores phone number string s in NVRAM at position n. None. 0–2 Example: AT&Z1=18005551212 stores the phone number 18005551212 in position 1. Use the DS=n command to recall and dial the number.
\An Selects maximum MNP block size. \A3 \A0 64 characters.
\A1 128 characters.
\A2 192 characters.
\A3 256 characters.
\Bn Sends break. \B3 1–9 Expressed in hundreds of milliseconds.
\Gn Sets modem port flow control. \G0 \G0 The modem processes XON/XOFF flow control characters locally.
\G1 The modem passes XON/XOFF flow control characters.
\X Sets XON/XOFF pass through. \X0 \X0 The modem processes XON/XOFF flow control characters locally.
\X1 The modem passes XON/XOFF flow control characters.
+A8E=n Sets V.8 operation. +A8E=1,1,C1,1 This is a compound parameter. The full syntax is as follows:

+A8E=<v8o>,<v8a>,<v8cf>,<v8b>

Valid values for <v8o>
Value Meaning
1 Enables DCE-controlled V.8 origination negotiation.
6 Enables DCE-controlled V.8 origination negotiation, issue +A8x indications.

Valid values for <v8a>
Value Meaning
1 Enable DCE-controlled V.8 answer negotiation.
5 Disable DCE-controlled V.8 answer negotiation, issue +A8x indications.

<v8cf> contains the V.8 CI signal call function octet. Valid values are 0–FF.

Valid values for <v8b>
Value Meaning
0 Disable V.8 negotiation.
1 Enable DCE-controlled V.8bis negotiation.
2 Enable DTE-controlled V.8 negotiation.
? Displays a list of valid +A8E settings.
+A8E? Display the current settings for V.8 or V.8 bis negotiation. None. None.
+A8T=n Sends a V.8 bis signal or message from the local DCE when V.80 is enabled None. This is a compound parameter. The full syntax is as follows:

+A8T=<signal>,<1st message>,<2nd message>,<sig en>,<msg en>,<supp delay>

Valid values for <signal>
Value Meaning
0 None.
1 Initiating Mre.
2 Initiating MRd.
3 Initiating CRe, low power.
4 Initiating CRe, high power.
5 Initiating CRd.
6 Initiating Esi.
7 Responding MRd, low power.
8 Responding MRd, high power.
9 Responding CRd.
10 Responding Esr.

Valid values for <sig_en>
Value Meaning
0 Enable detection of initiation signals (default).
1 Enable detection of responding signals .

Valid values for <msg_en>
Value Meaning
0 Enable detection of messages (default).
1 Enable detection of V.8 bis messages.

Valid values for <supp_delay>
Value Meaning
0 No delay inserted (default).
1 Insert 1.5 second delay between transmitted V.8 bis signal and the subsequent V.8 bis message.
? Displays a list of valid +A8T settings.
+A8T? Displays the current +A8T setting. None. None.
+DCS=n Selects the data compression algorithm. +DCS=1,1 This is a compound parameter. The full syntax is as follows:

+DCS=<v42bis>,<v44>

Valid values for <v42bis>
Value Meaning
0 Disable V.42bis.
1 Enable V.42bis.

Valid values for <v44>
Value Meaning
0 Disable V.44.
1 Enable V.44.
2 Enable V.44 for V.92 servers only.
+DR=n Controls data compression reporting. None. 0 Disables the compression report.
1 Enables the compression report.
? Displays a list of valid +DR settings.
+DS=n Configures the V.42 bis data compression method. +DS=3,0,1024,32 This is a compound parameter. The full syntax is as follows:

+DS=<direction>,<compression_negotiation>,<max_dict>,<max_string>

Valid values for <direction>
Value Meaning
0 Does not negotiate V.42 compression.
3 Negotiates V.42 compression in both directions.

For this modem, only direction is variable. The fixed values of the other parameters is as follows:

Parameter Fixed Value
compression_negotiation 0
max_dict 1024
max_string 32
+DS44=n Configures the V.44 data compression method. +DS44=3,0,0,1024,1024,
255,255,5120,4096
This is a compound parameter. The full syntax is as follows:

<direction>,<compression_negotiation>,<capability>
,<max_codewords_tx>,<max_codewords_rx>, <max_string_tx>,<max_string_rx>,<max_history_tx>,<max_history_rx>

Valid values for <direction>
Value Meaning
0 Does not negotiate V.44 compression.
3 Negotiates V.44 compression in both directions.

The value of compression_negotiation is always 0 (never disconnects if V44 is not negotiated).

The value of capability is always 0 (Stream method).

Valid Values for Remaining Parameters
Parameter Valid Values
max_codewords_tx 256–2048
max_codewords_rx 256–2048
max_string_tx 31–255
max_string_4x 31–255
max_history_tx 512–11008
max_history_4x 512–11008
+EB=n Determines the action taken when a break is received. +EB=0,,30 This is a compound parameter. The full syntax is as follows:

<break_selection>,<timed>,<default_length>

Valid Values for <break selection>
Value Meaning
0 Ignores break.
1 Nonexpedited, nondestructive.
2 Expedited, nondestructive.
3 Expedited, destructive.
? Displays a list of valid +EB settings.

This modem does not support the timed parameter.

Valid values for <default_length> are 30–90 in increments of 10. The unit of measure is milliseconds (ms).

+ER=n Controls error control reporting. +ER=0 0 Disables error control reporting.
1 Enables error control reporting.
? Displays a list of valid +ER settings.
+ESA Sets up error control parameters. None. This is a compound parameter. The full syntax is as follows:

+ESA=<trans_idle>,<frame_idle>,<framed_un_ov>,
<hd_auto>,<crc_type>,<nrzi_en>,<syn1>

This modem does not use the <framed_un_ov>, <hd_auto>, and <syn1> parameters.

Valid values for n
Combination Mode
0,,,,0,0,, Disables CRC generation and checking.
0,,,,1,0,, Causes the DCE to generate a 16-bit CRC in the transmit direction in framed sub-Mode and check the CRC in the receive direction.
+GCAP Displays supported capabilities. None. None.
+GCI=n Sets the country code. None.
Code Country   Code Country
09 Australia 6C Malaysia
0A Austria 73 Mexico
0F Belgium 7B Netherlands
20 Canada 7E New Zealand
31 Denmark 82 Norway
72 Europe 26 People's Republic of China
3C Finland 89 Philippines
3D France 8B Portugal
04 or 42 Germany 9C Singapore
46 Greece 9F South Africa
50 Hong Kong A0 Spain
51 Hungary A5 Sweden
53 India A6 Switzerland
54 Indonesia A9 Thailand
57 Ireland AE Turkey
59 Italy B4 United Kingdom
00 Japan B5 United States of America
61 Korea BC Vietnam

+GCI=? displays a list of valid country codes.

+ILRR=n Controls port rate reporting. +ILRR=0 0 Disables reporting of local port rate.
1 Enables reporting of local port rate.
? Displays a list of valid +ILRR settings.
+IPR=n Displays DTE to DCE transmission rates. None. ? Displays a list of supported transmission rates.
+ITF=n Sets the transmit flow control thresholds. None. off The signal threshold, in octets, above which the DCE will generate a flow-off signal.
on The signal threshold, in octets, below which the DCE will generate a flow-on signal.
? Displays a list of valid +ITF settings.
+MR=n Controls modulation reporting. None. 0 Enables modulation reporting.

The DCE transmits the +MRR:<rate>,<rx_rate>, and the +MCR:<carrier> intermediate result codes to the DTE.
The <carrier> reported is the current modulation; the <rate> is the transmit rate in bps or is zero if negotiation fails; the <rx_rate> is the receive channel rate and is only reported when different receive and transmit rates have been negotiated.
1 Disables modulation reporting.
? Displays a list of valid +MR settings.
+MS=n Controls modulation. +MS=V92,1,31200,
56000,31200,56000
This is a compound parameter. The full syntax is as follows:

+MS=<carrier>,<automode>,<min_rate>,
<max_rate>,<min_rx_rate>,<max_rx_rate>

Valid <carrier> values
Value Meaning
V92 V.92
V90 V.90
V34 V.34
V32B V.32bis
V32 V.32
V22B V.22bis
V22 V.22
Bell212A Bell 212A
V23C V.23, constant carrier, asymmetric FDM
V21 V.21
Bell103 Bell 103

Valid <automode> values
Value Meaning
0 Disables automatic modulation negotiation.

If a value is specified for <max_rate>, automatic rate selection is disabled and the modem will try to connect at the specified rate.

1 Enables automatic modulation negotiation.

Valid <min_rate> range
Value Meaning
31200 Determined by modulation selected in <carrier>
300–56000 Value limited by modulation selected in <carrier>.

Valid <min_rate> for each <carrier>
Value Meaning
V34 2400–33600 bps in steps of 2400 bps.
V32bis 4800–19200 bps in steps of 2400 bps.
V32 4800–14400 bps in steps of 2400 bps.
V22bis 2400 bps.
V22 2200 bps.
V23C Bell212A 1200 bps.
V.21, Bell103 300 bps.

Valid <max_rate> range
Value Meaning
56000 Determined by modulation selected in <carrier>
300–56000 Value limited by modulation selected in <carrier>.

Valid <max_rate> for each <carrier>
Value Meaning
V92 28000–56000 bps in steps of 1333 bps.
V90 28000–56000 bps in steps of 1333 bps.
V34 2400–33600 bps in steps of 2400 bps.
V32bis 4800–19200 bps in steps of 2400 bps.
V32 4800–14400 bps in steps of 2400 bps.
V22bis 2400 bps.
V22 2200 bps.
V23C, Bell212A 1200 bps.
V.21, Bell103 300 bps.
? Displays a list of valid +MS settings.
+VCID=n Controls Caller ID. +VCID=0 Note that this command is functionally the same as the #CID command.
0 Disables Caller ID.
1 Enables formatted Caller ID.
2 Enables unformatted Caller ID.
? Displays a list of valid #CID settings.

S-Registers

To change a setting, use the ATSr=n command, where r is the register number and n is a decimal value from 0 to 255 (unless otherwise indicated).

Example: ATS7=120 sets the time that the modem will wait for a connection from your carrier to 120 seconds.

To view a setting, use the ATSr? command, where r is the register number.

Note: These S-Register values are the default settings for North America. Your default settings may be different if you live outside North America.

Register Default Function
S0 0 Sets number of rings on which to answer in Auto Answer mode. When set to 0, Auto Answer is disabled.
S1 0 Counts and stores number of rings from an incoming call. (S0 must be greater than 0.)
S2 43 Stores ASCII decimal code for the escape code character. Default character is +. A value of 128–255 disables escape code.
S3 13 Stores ASCII code for the Carriage Return character. Valid range is 0–127.
S4 10 Stores ASCII decimal code for the Line Feed character. Valid range is 0–127.
S5 8 Stores ASCII decimal code for the Backspace character. A value of 128–255 disables Backspace key's delete function.
S6 4 Sets number of seconds modem waits before dialling. If Xn is set to X2 or X4, this is time-out length if no dial tone.
S7 50 Sets number of seconds modem waits for a carrier. May be increased as needed, for example to allow modem time to establish an international connection.
S8 2 Sets duration, in seconds, for pause (,) option in the Dial (Dn) command. Valid range is 0–32.
S9 6 Sets required duration, in tenths of a second, of remote modem's carrier signal before recognition by your USRobotics modem.
S10 60 Sets duration, in tenths of a second, that modem waits to hang up after loss of carrier. This guard time allows your modem to distinguish a line disturbance from a true disconnect (hang up) by the remote modem.
Note: If you set S10 = 255, the modem will not hang up when carrier is lost. Dropping DTR hangs up the modem.
S11 95 Sets duration and spacing, in milliseconds, of dialled tones.
S12 50 Sets duration, in fiftieths of a second, of guard time for escape code sequence (+++).
S18 0 Test timer for &T loopback testing. Sets the time in seconds of testing before the modem automatically times out and terminates the test. When set to 0, the timer is disabled. Valid range is 1–255.
S21 52 Sets length, in 10-millisecond units, of breaks sent from the modem to the computer; applies to MNP or V.42 mode only.
S22 119 Stores ASCII decimal code for the XON character.
S23 55 Stores ASCII decimal code for the XOFF character.
S24 60 Sets duration, in seconds, for the sleep mode timer. The timer activates when there is no activity in the off-line command state. At timeout, the modem goes into standby mode. S24 = 0 disables the timer. Valid range is 0, 5–65.
S28 1
Value Result
0 Disables V.34 modulation.
1 Enables V.34 modulation.
S30 0 Sets the duration, in minutes, for the inactivity timer. The timer activates when there is no data activity on the line; at timeout, the modem hangs up. S30=0 disables the timer. Valid range is 0–255.
S36 7 Specifies the action to be taken in the event of negotiation failure when error control is selected.
Used in conjunction with S48, LAPM error control and feature negotiation to negotiate certain connection types.

Value Result if S48=7 Result if S48=128
0 or 2 V.42 or hang up (Do not use)
1 or 3 V.42 or asynchronous Asynchronous
4 or 6 V.42, MNP, or hang up MNP or hang up
5 or 7 V.42, MNP, or asynchronous MNP or asynchronous
S37 0 Sets the maximum line data rate. In V.90 mode, sets the upstream V.34 rate.

Value Rate Value Rate
0 Auto rate 10 12000 bps
1 Reserved 11 14400 bps
2 1200/75 bps (V.23) 12 16800 bps
3 300 bps 13 19200 bps
4 Reserved 14 21600 bps
5 1200 15 24000 bps
6 2400 bps 16 26400 bps
7 4800 17 28800 bps
8 7200 18 31200 bps
9 9600 19 33600 bps
S38 1 Once a connection type (V.90) is determined, forces a particular downstream rate. A value of zero disables both connection types and allows a more reliable V.34 connection. The default value of 1 lets the modem select the downstream rate automatically. Other values force the downstream rate, with fallback to V.34 if unsuccessful at the configured rate.

Value Rate Value Rate
0 V.90 disabled 12 41333 bps
1 Auto rate 13 42666 bps
2 28000 bps 14 44000 bps
3 29333 bps 15 45333 bps
4 30666 bps 16 46666 bps
5 32000 bps 17 48000 bps
6 33333 bps 18 49333 bps
7 34666 bps 19 50666 bps
8 36000 bps 20 52000 bps
9 37333 bps 21 53333 bps
10 38666 bps 22 54666 bps
11 40000 bps 23 56000 bps
S48   Enables or disables error control and feature negotiation. Works in conjunction with S36 to determine the type of error correction method to use.

Value Result
7 Enables negotiation.
128 Disables negotiation.