The modem responds to the following AT+ command options.The letters AT (or at) must precede all commands except A/ and +++.
Factory-default options are underlined.
AT commands that begin with:
+D control data compression
+F control fax application operation
These commands are primarily used by software applications.
Command | Option | Description |
+A8E |
|
V.8 Configuration |
|
+A8=a,b,c,d |
|
|
a options: |
Specifies V.8 origination negotiation options |
|
0 |
Disable |
|
1 |
Enable computer-controlled V.8 origination negotiation |
|
6 |
Enable computer-controlled V.8 origination negotiation with +A8x indications |
|
b options: |
Specifies V.8 answer negotiation options |
|
0 |
Disable |
|
1 |
Enable computer-controlled V.8 answer negotiation |
|
5 |
Enable computer-controlled V.8 answer negotiation with +A8x indications |
|
c options: |
Specifies the V.8 CI Signal Call Function Octet options |
|
00h - FFh, default=00h |
|
|
d options: |
Specifies V.8 control options |
|
0 |
Disabled |
|
1 |
Enabled, modem control |
|
2 |
Enabled, computer control |
+A8T |
|
V.8bis Signal and Message Control |
|
+A8T=a,b,c,d,e,f |
|
|
a options: |
Specifies V.8bis Signal to Transmit |
|
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 |
|
b options: |
Specifies V.8bis Transmit Message 1 |
|
|
hexadecimal octet coded string |
|
c options: |
Specifies V.8bis Transmit Message 2 |
|
|
hexadecimal octet coded string |
|
d options: |
Specifies V.8bis signal detection |
|
0 |
Enable detection of initiating V.8bis signal |
|
1 |
Enable detection of responding V.8bis signal |
|
2 |
Enable detection of both V.8bis signals |
|
e options: |
Specifies V.8bis message detection |
|
0 |
Disable detection |
|
1 |
Enable detection |
|
f options: |
Specifies the V.8bis message delay |
|
0 |
No delay between transmitting signal and messages |
|
1 |
1.5 second delay between transmitting signal and any message |
+DR |
|
Data Compression (DC) Reporting |
|
+DR=0 |
Disabled |
|
+DR=1 |
Enabled |
+DS |
|
Data Compression Control |
|
+DS=p,q,r,s |
|
|
p options: |
Specifies compression on/off direction |
|
0 |
No compression |
|
1 |
Tx direction only |
|
2 |
Rx direction only |
|
3 |
Both directions; accept any direction |
|
q options: |
Specifies negotiation |
|
0 |
Do not disconnect if data compression is not negotiated per Direction option |
|
1 |
Disconnect if data compression is not negotiated per Direction option |
|
r options: |
Specifies maximum dictionary size |
|
512 - 65535 |
Default = 2048 |
|
s options: |
Specifies maximum string size |
|
6 - 250 |
Default = 32 |
+EB |
|
Break Handling Control |
|
+EB=p,q r |
|
|
p options: |
Specifies break selection |
|
0 |
Ignore break |
|
1 |
Non-expedited, non-destructive |
|
2 |
Expedited, non-destructive |
|
3 |
Expedited, destructive |
|
q options: |
Specifies break length control |
|
0 |
Transmission of V.42 L-SIGNAL does not indicate break length |
|
1 |
Transmission of V.42 L-SIGNAL indicates break length |
|
r options: |
Specifies the default break-length |
|
0 |
Break is not transmitted to the computer |
|
1- 254, default=100 |
Break length, in 0.01-second increments |
+ER |
|
Error-Control Reporting |
+ER=a |
|
|
|
a options: |
Specifies the modem’s error-control reporting activity |
|
0 |
Disabled |
|
1 |
Enabled: modem issues one of the following messages to the computer, before it issues a connect message. The message specifies the Error Correction protocol negotiated: +ER:NONE +ER:LAPM +ER:ALT |
+ES |
|
Error-Correction (EC) Control |
|
+ES=p,q r |
|
|
p options: |
Specifies the originate-modem’s Request Error Correction mode |
|
0 |
Direct mode |
|
1 |
Normal mode |
|
2 |
LAP-M Only |
|
3 |
LAP-M or MNP |
|
4 |
MNP Only |
|
6 |
Initiate Sync Access mode when connection is established |
|
q options: |
Specifies the answer-modem’s Fallback Error Correction mode |
|
0 |
EC optional, fallback to Normal mode |
|
1 |
EC optional, fallback to Direct mode |
|
2 |
EC required (LAP-M or MNP) |
|
3 |
EC required (LAP-M only) |
|
4 |
EC required (MNP only) |
|
r options: |
Specifies the originate-modem’s Fallback Error Correction mode |
|
0 |
Direct mode |
|
1 |
Normal mode |
|
2 |
EC optional, fallback to Normal mode |
|
3 |
EC optional, fallback to Direct mode |
|
4 |
EC required (LAP-M or MNP) |
|
5 |
EC required (LAP-M only) |
|
6 |
EC required (MNP only) |
|
8 |
Initiate synchronous access mode when connected |
+ESA |
|
Synchronous Access Mode Configuration |
|
+ESA=a,b,c,d,e,f |
|
|
a options: |
Specifies the Idle in Transparent sub-mode |
|
0 |
Computer transmits 8 bit SYN sequence on idle. Computer does not hunt for synchronization sequence |
|
b options: |
Specifies the Idle in Framed sub-mode |
|
0 |
Computer transmits HDLC flags on idle |
|
c options: |
Specifies under-run and over-run in Framed sub-mode |
|
0 |
Computer transmits Abort on an under-run within a frame |
|
1 |
Computer transmits a Flag on an under-run within a frame, and notifies the modem of any under-run or over-run |
|
d options |
Specifies half-duplex control. Not available. |
|
e options |
Specifies the Cyclic Response Code (CRC) type |
|
0 |
Disabled. No CRC generation or checking. |
|
1 |
In Framed sub-mode, the computer generates 16-bit CRC in the Transmit direction and the modem generates 16-bit CRC on the Receive direction. |
|
f options: |
Specifies Non-Return to Zero (NRZI) options |
|
0 |
NRZI encoding and decoding are disabled. |
+ETBM |
|
Disconnect Buffer Delay Control |
|
+ETBM=p,q r |
|
|
p options: |
Specifies the disconnect buffer delay with pending transmit data |
|
0 |
Discard buffered data and disconnect |
|
1 |
Attempt to transmit until all data is delivered, then disconnect. Ignore timer. |
|
2 |
Attempt to transmit until all data is delivered or timer expires. |
|
q options: |
Specifies the disconnect buffer delay with pending receive data |
|
0 |
Discard buffered data and disconnect |
|
1 |
Attempt to transmit until all data is delivered, then disconnect. Ignore timer. |
|
2 |
Attempt to transmit until all data is delivered or timer expires. |
|
r options: 1-255, default=0 |
Disconnect buffer delay timer, in 1-second increments |
+FCLASS |
|
Fax/Data Mode |
|
+FCLASS=0 |
Data Mode |
|
+FCLASS=1 |
|
|
+FCLASS=8 |
Voice Mode (Not available in Data/Fax and Data/Fax/TAM modems.) |
+FLO |
|
Fax Flow Control |
|
+FLO=0 |
None |
|
+FLO=1 |
XON/XOFF |
|
+FLO=2 |
RTS/CTS |
+FMI? |
|
Report Manufacturer ID |
+FMM? |
|
Report Modem ID |
+FMR? |
|
Report Revision Level |
+FRH |
|
Receive High-Level Data Link Control (HDLC) Mode Sets mode and transmit/receive rate for faxes |
|
+FRH=3 |
V.21 at 300 bps |
|
+FRH=24 |
V.27ter at 2.4 Kbps |
|
+FRH=48 |
V.27ter at 4.8 Kbps |
|
+FRH=72 |
V.27ter at 7.2 Kbps |
|
+FRH=73 |
V.27ter at 7.2 Kbps with long train time |
|
+FRH=74 |
V.27ter at 7.2 Kbps with short train time |
|
+FRH=96 |
V.29 at 9.6 Kbps |
|
+FRH=97 |
V.17 at 9.6 Kbps with long train time |
|
+FRH=98 |
V.17 at 9.6 Kbps with short train time |
|
+FRH=121 |
V.17 at 12.0 Kbps with long train time |
|
+FRH=122 |
V.17 at 12.0 Kbps with short train time |
|
+FRH=145 |
V.17 at 14.4 Kbps with long train time |
|
+FRH=146 |
V.17 at 14.4 Kbps with short train time |
+FRM |
+FRM |
Receive Mode Sets the modulation mode for receiving faxes |
|
+FRMm |
Use mode m; see mode options for +FRH, above. |
+FRS |
|
Wait for Silence |
|
+FRSn |
Wait (n*10) ms; n=0 to 255 |
+FTH |
+FTH |
Transmit High-Level Data Link Control (HDLC) Mode |
|
+FTHmode |
Use mode mode; see options for +FRH, above. |
+FTM |
+FTM |
Transmit Mode Sets the modulation mode for transmitting faxes |
|
+FTMmode |
Use mode mode; see options for +FRH, above. |
+FTS |
|
Pause Transmission |
|
+FTSn |
Pause transmission for (n*10) ms; n=0 to 255 |
+GCAP |
|
Report Capabilities |
|
+GCAP |
Display modem capabilities |
+GCI |
|
Country of Installation |
+GCI=a |
Set country in which modem is installed |
|
00 |
Japan |
|
04 |
Germany |
|
07 |
Argentina |
|
09 |
Australia |
|
0A |
Austria |
|
0F |
Belgium |
|
16 |
Brazil |
|
|
1B |
Bulgaria |
20 |
Canada |
|
25 |
Chile |
|
26 |
China |
|
27 |
Columbia |
|
2E |
Czech Republic |
|
|
2D |
Cyprus |
31 |
Denmark |
|
3C |
Finland |
|
3D |
France |
|
42 |
Germany |
|
50 |
Hong Kong |
|
57 |
Ireland |
|
58 |
Israel |
|
59 |
Italy |
|
5E |
Jordan |
|
61 |
Korea |
|
|
68 |
Liechtenstein |
6C |
Malaysia |
|
|
70 |
Malta |
7B |
Netherlands |
|
82 |
Norway |
|
8B |
Portugal |
|
|
8C |
Puerto Rico |
9C |
Singapore |
|
9F |
South Africa |
|
A0 |
Spain |
|
A5 |
Sweden |
|
A6 |
Switzerland |
|
A9 |
Thailand |
|
AE |
Turkey |
|
B4 |
United Kingdom |
|
B5 |
USA |
|
BB |
Venezuela |
|
BC |
Vietnam |
|
+GMI |
|
Request Manufacturer ID |
|
+GMI? |
Display modem-manufacturer information |
+GMM |
|
Request Model ID |
|
+GMM? |
Display modem-model information |
+GMR |
|
Request Software Revision Number |
|
+GMR? |
Display modem-software revision number |
+IFC |
|
Flow Control |
|
+IFC=p,q |
|
|
p options: |
Specifies the computer’s flow control method for data passing to the modem (downstream) |
|
0 |
None |
|
1 |
XON/XOFF flow control, no pass-through |
|
2 |
RTS flow control |
|
3 |
XON/XOFF flow control, with pass-through |
|
q options: |
Specifies the modem’s flow control method for data passing from the modem (upstream) |
|
0 |
None |
|
1 |
XON/XOFF flow control, no pass-through |
|
2 |
CTS flow control |
+ILRR |
|
Computer’s Local Rate Reporting |
|
+ILRR=0 |
Disabled |
|
+ILRR=1 |
Enabled |
+ITF |
|
Transmit Flow Control Thresholds (V.80) |
|
+ITF=a,b |
|
|
a options: |
Specifies the threshold, in octets, at which the modem turns transmit flow-control off |
|
0-2047 default=255 |
|
|
b options: |
Specifies the threshold, in octets, at which the modem turns transmit flow-control on |
|
0-2047 default=255 |
|
+MR |
|
Modulation Mode Reporting |
|
+MR=0 |
Disabled |
|
+MR=1 |
Enabled |
+MS |
|
Modulation Control |
|
+MS=p,q,r,s,t,u |
|
|
p options: |
Specifies the modulation mode |
|
V21 |
V.21 |
|
V22 |
V.22 |
|
V22B |
V.22bis |
|
V23C |
V.23c |
|
V32 |
V.32 |
|
V32B |
V.32bis |
|
V34 |
V.34 |
|
K56FLEX |
K56flex™
|
|
V90 |
V.90
|
|
V92 |
V.92 |
|
q options: |
Specifies the Automode option |
|
0 |
Disabled |
|
1 |
Enabled |
|
r options: |
Specifies the minimum data rate in the Tx direction |
|
0 |
Use the minimum rate of the specified modulation mode (300 bps) |
|
300 - 33600 |
bps |
|
s options: |
Specifies the maximum data rate in the Tx direction |
|
0 |
Use the maximum rate of the specified modulation mode |
|
300 - 33600 |
bps |
|
t options: |
Specifies the minimum data rate in the Rx direction |
|
0 |
Use the minimum rate of the specified modulation mode |
|
300 - 60000 |
bps |
|
u options: |
Specifies the maximum data rate in the Rx direction |
|
0 |
Use the maximum rate of the specified modulation mode |
|
300 - 60000 |
bps |
+VCID |
|
Caller ID Control |
|
|
This option takes effect only where the function is supported. Data/Fax modems do not support this option. |
|
+VCID=0 |
Disable |
|
+VCID=1 |
Enable |
|
+VCID=? |
Display Caller ID Status (returns 0 or 1) |
+VDR |
|
Distinctive Ring Control and Report |
|
|
This option takes effect only where the function is supported. Data/Fax modems do not support this option |
|
+VDR=m,n |
|
|
m options: |
Specifies control |
|
0 |
Disable |
|
1 |
Enable |
|
n options: |
Specifies reporting |
|
0 |
Produce DROFF/DRON report, no RING |
|
1-255 |
Produce DROFF/DRON, followed by RING after delay of n/10 seconds |
+VEM |
|
Event Reporting and Masking Control |
Data/Fax/Speakerphone modem only |
||
|
|
Bit-mapped event control mask. See Event Reporting Word>. |
+VGR |
|
Receive Gain |
Data/Fax/Speakerphone modem only |
||
|
0 |
Automatic Gain Control |
|
1-255 |
Relative range, where 128 indicates a nominal value. |
+VGT |
|
Transmit Volume |
Data/Fax/Speakerphone modem only |
||
|
1-255 |
Relative range, where 128 indicates a nominal value. |
+VIP |
|
Initialize Voice Parameters |
Data/Fax/Speakerphone modem only |
||
|
|
Set speakerphone parameters to factory-default options. |
+VLS |
|
Select Analog Source and Destination |
Data/Fax/Speakerphone modem only |
||
|
0 |
DCE (modem) on-hook |
|
1 |
DCE off-hook, DCE connected to telco |
|
8 |
DCE on-hook, DCE connected to speaker |
|
9 |
speakerphone with mute enabled |
|
11 |
DCE on-hook, DCE connected to microphone |
|
13 |
DCE off-hook, DCE connected to telco, speaker, and microphone (speakerphone) |
+VNH |
|
Automatic Hangup Control |
Data/Fax/Speakerphone modem only |
||
|
+VNH=0 |
Retain automatic hang-ups |
|
+VNH=1 |
Disable DCE-initiated automatic hang-ups |
|
+VNH=2 |
Disable all Automatic hang-ups |
+VPR |
|
Voice DTE-DCE Rate |
Data/Fax/Speakerphone modem only |
||
|
+VPR=0 |
Autobaud |
+VRA |
|
Ringback Gone Timer |
Data/Fax/Speakerphone modem only |
||
|
|
If, after detecting ringback, no further ringbacks are detected after n/10 seconds, operate as if the remote device answered the call. |
|
+VRA=n |
If no ringback is received, after n/10 seconds, assume that the remote device has answered the call; n = 0-255 |
|
|
Ringback Never Occurred |
|
+VRN=n |
After n/10 seconds, operate as if ringback never occurred; n = 0-255 |
+VRX |
|
Voice Receive Mode |
Data/Fax/Speakerphone modem only |
||
|
|
Determines whether the modem generates a periodic beep, audible to both parties on the speakerphone, indicating that the call is being recorded. |
|
|
|
|
+VRX or +VRX=0 |
Produce Periodic DCE Tone While Recording |
|
+VRX=1 |
Disable Periodic DCE Tone Production During Recording |
+VSD |
|
Remote Silence-Detection Properties |
Data/Fax/Speakerphone modem only |
||
|
+VSD=m,n |
Used in answering-machine mode. Specifies the volume and duration thresholds that determine whether the remote device has hung up. |
|
m options: |
Specifies the silence-detection level |
|
0 |
Use current +VSM value; or, if current +VSM value is 0, use 128. |
|
127 |
Low Threshold (most sensitive) |
|
128 |
Medium Threshold |
|
129 |
High Threshold (least sensitive) |
|
n options: |
Specifies the silence-detection duration |
|
0 |
Disable |
|
1-255 |
Detect n/10 secnds silence; n = 0-255 |
|
60 |
Default = 6 seconds |
+VSM |
|
Speech Compression Properties |
Data/Fax/Speakerphone modem only |
||
|
+VSM=m,n,p,q |
Specifies the speakerphone compression parameters |
|
m options: |
Specifies the compression method |
|
128 |
PCM |
|
129 |
ADPCM |
|
n options: |
Specifies the sampling rate to determine whether to compress |
|
8000 |
8000 Hz |
|
p options: |
Parameter p specifies compression and expansion of periods of silence. These parameters are not implemented in Release 1.0. You may leave them blank or enter the value 0. |
|
0 |
Disable |
|
q options: |
Parameter q specifies compression and expansion of periods of silence. These parameters are not implemented in Release 1.0. You may leave them blank or enter the value 0. |
|
0 |
Disable |
+VTD |
|
Dual Tone Multi-Frequency (DTMF) Tone Duration |
Data/Fax/Speakerphone modem only |
||
|
+VTDn |
Generates tone for n/100 seconds; n = 0-255. Default=100. |
+VTS |
|
DTMF Tone Generation Properties |
Data/Fax/Speakerphone modem only |
||
|
|
+VTS accepts multiple options, separated by commas, of any of the following types. Use square or curly brackets as shown. |
|
D |
Generate default DTMF Tone, default duration. |
|
{t,n} |
t specifies a DTMF tone; t = 0-9 n specifies tone duration n/100 seconds; n = 1-500 |
|
{f,g,n} |
f and g specify a tone pair, f Hz and g Hz; in the range n Specifies tone-pair duration n/100 seconds; n = 1-500 |
|
Example: |
AT+VTS=4,{},[1000,1300,50],8,{*,5},[,,100],5 This example specifies the following sequence: 1. Play DTMF 4 for the duration stored in +VTD 2. Play silence for the duration stored in +VTD 3. Play tone pair at 1000 Hz and 1300 Hz for 500 ms 4. Play DTMF 8 for a duration stored in +VTD 5. Play DTMF * for 50 ms 6. Play silence for 1 second 7. Play DTMF 5 for the duration stored in +VTD |
+VTX |
|
Enter Voice-Transmission Mode |
Data/Fax/Speakerphone modem only |
||
|
|
|