Table 1: AT and AT& Commands
Command | Option | Description |
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|
|
T | T | Tone Dial |
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| This command instructs the modem to use DTMF tone |
|
| dialing. |
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| Example: ATDT5554678. |
|
| This command uses DTMF tone Dialing to dial the number |
|
| 5554678 |
V |
|
|
|
| Determines whether the modem sends short- or |
|
| messages to the communications application, indicating |
|
| the connection status, rate, and mode. |
|
|
|
| V0 | Return Numeric Code (Short Form) |
|
|
|
| V1 | Return Text (Long Form) |
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|
|
X |
| Select |
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|
|
| X0 | No Carrier; Connect. Modem reports lack of a carrier sig- |
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| nal; connection success/failure; modem dials without wait- |
|
| ing for a dial tone |
| X1 | No Carrier; Connect; Connect <rate>. Modem reports lack |
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| 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/ |
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| failure; the computer data rate established; and the lack of |
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| a dial tone |
|
|
|
| X3 | No Carrier; Connect; Connect <rate>; |
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| reports lack of a carrier signal; connection success/failure; |
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| the computer data rate established; and the presence of a |
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| busy signal |
| X4 | No Carrier; Connect; Connect <rate>; No |
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| tone. Modem reports lack of a carrier signal; connection |
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| success/failure; the computer data rate established; the lack |
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| 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 |
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| asserted to |
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|
|
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