The modem responds to the following AT and AT& command options.
The letters AT (or at) must precede all commands except A/ and +++. Factory-default options are underlined.
Command | Option | Description |
A |
(none) |
Answer incoming call |
A/ |
(none)
|
Repeat Last Command Re-issues the previous command to the modem. (Do not press Return; the command executes as soon as the / is pressed.) |
D |
(none)
|
Dial a Number Instructs the modem to dial the telephone number that you enter immediately after the ATD command. Example: ATD5554678.
|
E |
Echo Async (Keyboard) Input to Terminal Determines whether the characters you type at the keyboard are displayed (echoed) to the terminal-emulation window (if it is active) or to the communications application. |
|
|
E0 |
Disable |
|
E1 |
Enable |
H |
Hook |
|
|
H0 |
Go on Hook (disconnect from the telephone line; hang up) |
|
H1 |
Go off Hook (connect to the telephone line) |
I |
Request Information From Modem |
|
|
I0 |
“5600” |
|
I1 |
“255” |
|
I2 |
“OK” |
|
I3 |
Software Version |
|
I4 |
“OK” |
|
I5 |
Disconnect Reason |
|
I6 |
Country Code |
|
I7 |
Product Code |
L |
Speaker Volume This parameter determines the volume, for call-progress monitor only, of sounds such as dialing, ringing, busy, negotiation. |
|
|
L0, L1 |
Low |
|
L2 |
Medium |
|
L3 |
High |
M |
Speaker Control |
|
|
M0 |
Off |
|
M1 |
On During Training Only |
|
M2 |
Always On |
|
M3 |
Off during dialing; on during call progress; off during data transfer |
O |
Return to On-Line Mode This parameter determines whether the modem initiates a retrain after changing from escape mode to data mode, or after a semi-colon in dial strings. |
|
|
O0 |
No Retrain |
|
O1 |
Retrain |
|
O2 |
Initiate Rate Renegotiation |
|
O3 |
Rate Renegotiation with silence |
P |
P |
Pulse Dial |
Q |
Result-Code Display The modem can send result codes and connect messages to the computer as a result of connecting or failing to connect; establishing a data rate; and establishing error-correction and data-compression protocols. Refer to: ATV; AT\V; ATX. |
|
|
Q0 |
Enable display |
|
Q1 |
Disable display |
T
|
T
|
Tone Dial This command instructs the modem to use DTMF tone dialing. |
V
|
Result-Code Format Determines whether the modem sends short- or long-form messages to the communications application, indicating the connection status, rate, and mode. |
|
|
V0 |
Return Numeric Code (Short Form) |
|
V1 |
Return Text (Long Form) |
X |
|
Select Call-Progress Result Codes to Return |
|
X0 |
No Carrier; Connect. Modem reports lack of a carrier signal; connection success/failure; modem dials without waiting for a dial tone |
|
X1 |
No Carrier; Connect; Connect <rate>. Modem reports lack of a carrier signal; connection success/failure, and the computer data rate established |
|
X2 |
No Carrier; Connect; Connect <rate>; No Dial Tone. Modem reports lack of a carrier signal; connection success/failure; the computer data rate established; and the lack of a dial tone |
|
X3
|
No Carrier; Connect; Connect <rate>; Busy-tone. Modem reports lack of a carrier signal; connection success/failure; the computer data rate established; and the presence of a busy signal |
|
X4
|
No Carrier; Connect; Connect <rate>; No Dial-tone; Busy-tone. Modem reports lack of a carrier signal; connection success/failure; the computer data rate established; the lack of a dial tone; and the presence of a busy signal |
Z |
Z |
Reset Modem Parameters to Default Configuration |
&C |
|
DCD Control |
|
&C0 |
Always Asserted |
|
&C1 |
Asserted in Data Mode Only |
&D
|
|
DTR Control Determines how modem responds to DTR signal from DTE. |
|
&D0 |
Ignore DTR |
|
&D1 |
Enter Command mode when DTR transitions from asserted to de-asserted |
|
&D2 |
Disconnect call when DTR transitions from asserted to de-asserted |
|
&D3 |
Reset modem parameters to default configuration when DTR transitions from asserted-to-de-asserted |
&F |
Initialize modem to default factory configuration. |
|
&G |
|
Guard Tone |
|
&G0 |
Off |
|
&G1 |
550 Hz Guard Tone |
|
&G2 |
1800 Hz Guard Tone |
&I |
|
Dial TX Level |
|
&In |
Level n; n = 0 to 15. Default = 9 |
|
&I99 |
Automatic Level |
&P |
Pulse Cycle Used when the modem is instructed to pulse dial. |
|
|
&P0 |
40/60 Make/Break Ratio |
|
&P1 |
33/67 Make/Break Ratio |
|
&P2 |
38/62 Make/Break Ratio |
&R |
CTS Control |
|
|
&R0 |
Normal |
|
&R1 |
Always On |
&S |
DSR Control |
|
|
&S0 |
Always On |
|
&S1 |
On When Modem Recognizes Remote |
&T |
Test |
|
|
&T0 |
Terminate Test |
|
&T1
|
Initiate Local Analog Loopback Test Disconnect the telephone line from the modem line input connector before using this command. Set S-Register 46 = 23 (ATS46=23) before executing &T1. |
&V |
Modem Status |
|
|
&V0 |
Short Form Report |
|
&V1 |
Current or Last Connection Report |
|
&V2 |
Long Form Report |
Table 1: AT and AT& Commands