Certain modem values, or parameters, are stored in memory locations called S-registers. Use the S command to read or to alter the contents of S-registers (see Data Commands).
| Register | Unit | Range | Default | Description | ||
|---|---|---|---|---|---|---|
| S0 | 1 ring | 0, 1–255 | 1 | Sets the number of rings until the modem answers. ATS0=0 disables autoanswer completely. | ||
| S1 | 1 ring | 0–255 | 0 | Counts the rings that have occurred. | ||
| S2 | decimal | 0–127 128–255 |
43 (+) | Sets ASCII code for the escape sequence character. Values greater than 127 disable escape. | ||
| S3 | decimal | 0–127 | 13 (^M) | Sets the ASCII code for the carriage return character. | ||
| S4 | decimal | 0–127 | 10 (^J) | Sets the ASCII code for the line feed character. | ||
| S5 | decimal | 0–32 33–127 |
8 (^H) | Sets the ASCII code for the backspace character. Values greater than 32 disable backspace. | ||
| S6 | seconds | 2–65* | 2* | Sets the time the modem waits after it goes off-hook before it begins to dial the telephone number. | ||
| S7 | seconds | 1–255* | 50* | Sets the time the modem waits for a carrier signal before aborting a call. Also sets the wait-for-silence time for the @ dial modifier | ||
| S8 | seconds | 0–65 | 2 | Sets the length of a pause caused by a comma character in a dialing command. | ||
| S9 | decimal | 0, 1–127 | 37 (%) | Sets ASCII code for remote configuration escape character. S9=0 disables remote configuration. | ||
| S10 | 100 ms | 1–254 | 20 | Sets how long a carrier signal must be lost before the modem disconnects. | ||
| S11 | 1 ms | 50–150* | 95* | Sets spacing and duration of dialing tones. | ||
| S28 | decimal | 0, 1–255 | 1 | 0 disables, 1–255 enables V.34 modulation. | ||
| S30 | 1 minute | 0, 1–255 | 0 | Sets the length of time that the modem waits before disconnecting when no data is sent or received. A value of zero disables the timer. See also the \T command. | ||
| S35 | decimal | 0–1 | 0 | 0 disables, 1 enables the V.25 data calling tone, which allows remote data/fax/voice discrimination. | ||
| S36 | decimal | 0–7 | 7 | Specifies the action to take in the event of a negotiation failure when error control is selected. (See S48.) | ||
| S37 | decimal | 0–19 | 0 | Sets the maximum V.34 "upstream" speed at which the modem attempts to connect. | ||
| Value 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 |
Speed maximum modem speed reserved 1200/75 bps 300 bps reserved 1200 bps 2400 bps 4800 bps 7200 bps 9600 bps 12000 bps 14400 bps 16800 bps 19200 bps 21600 bps 24000 bps 26400 bps 28800 bps 31200 bps 33600 bps |
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| S38 | decimal | 0–23 | 1 | Sets the maximum 56K "downstream" speed at which the modem attempts to connect. The default maximum speed is 56K bps. | ||
| Value 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 |
V.90 mode 56K disabled 56K autorate 28000 bps 29333 bps 30666 bps 32000 bps 33333 bps 34666 bps 36000 bps 37333 bps 38666 bps 40000 bps 41333 bps 42666 bps 44000 bps 45333 bps 46666 bps 48000 bps 49333 bps 50666 bps 52000 bps 53333 bps 54666 bps 56000 bps |
K56flex mode 56K disabled 56K autorate 32000 bps 34000 bps 36000 bps 38000 bps 40000 bps 42000 bps 44000 bps 46000 bps 48000 bps 50000 bps 52000 bps 54000 bps 56000 bps |
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| S42 | decimal | 0–1 | 1 | Enables/disables the 56K auto rate. When 56K auto is disabled, fallback to V.34 is also disabled. 0 = disable; 1 = enable. | ||
| S43 | decimal | 0–1 | 1 | For testing and debugging only. Enables/disables V.32bis start-up auto mode operation. 0 = disable; 1 = enable. | ||
| S48 | decimal | 7 or 128 | 7 | Enables (7) or disables (128) LAPM negotiation. The following table lists the S36 and S48 configuration settings for certain types of connections. | ||
S36=0, 2 S36=1, 3 S36=4, 6 S36=5, 7 |
S48=7 LAPM or hangup LAPM or async LAPM, MNP, or hangup LAPM, MNP or async |
S48=128 Do not use Async MNP or hangup MNP or async |
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| S89 | seconds | 0, 5–255 | 10 | Sets the length of time in the off-line command mode before the modem goes into standby mode. A value of zero prevents standby mode; a value of 1–4 sets the value to 5. | ||
| S108 | decimal | 0–3, 6, 7 | 6 | Selects the 56K digital loss if using the modem through a PBX line. The default value is -6 dB loss, the value used when calling from a typical POTS line long distance. | ||
| Value 0 1 2 3 6 7 |
Digital loss -0 dB, no robbed-bit signaling -3 dB PBX -2 dB -3 dB -6 dB -0 dB with robbed-bit signaling |
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| S109 | decimal | 0–2 | 1 | Selects the 56K operating mode. | ||
| Value 0 1 2 |
56K mode K56flex mode (V.90 disabled) Dual mode (K56flex or V.90) V.90 mode (K56flex disabled) |
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* These values may be different outside North America.