Modem operation is controlled by generic AT commands. These AT commands may be basic AT (i.e., commands preceded by AT, AT&, AT%), or S register (e.g., S6=n). Under the AT command set (with the exception of the A/ command), each command line must begin with the character sequence AT. Commands entered in upper case or lower case are accepted, but both the A and T must be of the same case. The AT sequence may be followed by any number of commands in sequence, except for commands such as Z, D, or A. Commands following commands Z, D, or A on the same command line will be ignored. The maximum number of characters on any command line is 256 (including "A" and "T"). Below is a pertial list of AT commands and S registers. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ A/ - Re-execute Command A - Answer the phone. Dn - Dial This command directs the modem to go on-line, dial according to the string entered and attempt to establish a connection. Punctuation characters may be used for clarity, with parentheses, hyphen, and spaces being ignored. 0-9 DTMF digits 0 to 9. * The 'star' digit (tone dialling only). # The 'gate' digit (tone dialling only). P Select pulse dialling T Select tone dialling R This command will be accepted, but not acted on. ! Hook-Flash W Wait for dial tone: the modem will wait for dial tone before dialling the digits following "W". @ Wait for silence: the modem will wait for at least 5 seconds before continuing with the next dial string parameter. , Dial pause ; Return to command state. ^ Disable calling tone: applicable to current dial attempt only. ( ) Ignored: may be used to format the dial string. - Ignored: may be used to format the dial string. Ignored: may be used to format the dial string. Invalid character: will be ignored. > If enabled by country specific parameter, the modem will generate a grounding pulse on the EARTH relay output. En - Command Echo E0 Disables command echo. E1 Enables command echo. Hn - Disconnect (Hang-Up) H0 The modem will release the line if the modem is currently on-line. H1 If on-hook, the modem will go off-hook and enter command mode. In - Identification I0 Reports product code . I1 Reports pre-computed checksum from ROM. I2 Computes checksum and compares it with value stored in ROM. I3 Reports firmware revision model code I4 Reports OEM defined identifier string I5 Reports Country Code parameter . Ln - Speaker Volume L0 Low volume. L1 Low volume. L2 Medium volume. L3 High volume. Mn - Speaker Control M0 Speaker is always off. M1 Speaker is on during call establishment, but off when receiving carrier. M2 Speaker is always on. M3 Speaker is off when receiving carrier and during dialling, but on during answering. On - Return to On-Line Data Mode O0 Enters on-line data mode without a retrain. O1 Enters on-line data mode with a retrain before returning to on-line data mode. P - Set Pulse Dial Default Qn - Quiet Results Codes Control Q0 Enables result codes to the DTE. Q1 Disables result codes to the DTE. T - Set Tone Dial Default Vn - Result Code Form V0 Enables short-form (terse) result codes. Line feed is not issued before a short-form result code. V1 Enables long-form (verbose) result codes. Zn - Soft Reset and Restore Profile Z0 Soft reset and restore stored profile 0. Z1 Soft reset and restore stored profile 1. &Cn - RLSD (DCD) Option &C0 RLSD remains ON at all times. &C1 RLSD follows the state of the carrier. &Dn - DTR Option &D0 - DTR drop is interpreted according to the current &Q setting as follows: &Q0, &Q5, &Q6 DTR is ignored (assumed ON). Allows operation with DTEs which don't provide DTR. &Q1, &Q4 DTR drop causes the modem to hang up. Auto-answer is not affected. &Q2, &Q3 DTR drop causes the modem to hang up. Auto-answer is inhibited. &D1 DTR drop is interpreted according to the current &Q setting as follows: &Q0, &Q1, &Q4, &Q5, &Q6 DTR drop is interpreted by the modem as if the asynchronous escape sequence had been entered. The modem returns to asynchronous command state without disconnecting. &Q2, &Q3 DTR drop causes the modem to hang up. Auto-answer is inhibited. &D2 DTR drop is interpreted according to the current &Q setting as follows: &Q0 through &Q6 DTR drop causes the modem to hang up. Auto-answer is inhibited. &D3 DTR drop is interpreted according to the current &Q setting as follows: &Q0, &Q1, &Q4, &Q5, &Q6 DTR drop causes the modem to perform a soft reset as if the Z command were received. The &Y setting determines which profile is loaded. &Q2, &Q3 DTR drop causes the modem to hang up. Auto-answer is inhibited. &F - Restore Factory Configuration &Gn - Select Guard Tone &G0 Disables guard tone. &G1 Disables guard tone. &G2 Selects 1800 Hz guard tone. &Kn - Flow Control &K0 Disables flow control. &K3 Enables RTS/CTS flow control. (Default for data modem modes.) &K4 Enables XON/XOFF flow control. &Ln - Leased Line Operation &L0 Selects dial-up line operation. &L1 Selects leased line operation. &Mn - Asynchronous/Synchronous Mode Selection &M0 Selects direct asynchronous operation. &M1 Selects synchronous connect mode with async off-line command mode. &M2 Selects synchronous connect mode with async off-line command mode. &M3 Selects synchronous connect mode. &Pn - Select Pulse Dial Make/Break Ratio &P0 Selects 39%-61% make/break ratio at 10 pulses per second. &P1 Selects 33%-67% make/break ratio at 10 pulses per second. &P2 Selects 39%-61% make/break ratio at 20 pulses per second. &P3 Selects 33%-67% make/break ratio at 20 pulses per second. &Qn - Sync/Async Mode &Q0 Selects direct asynchronous operation. See &M0. &Q1 Selects synchronous connect mode with async off-line command mode. &Q2 Selects synchronous connect mode with async off-line command mode. &Q4 Selects AutoSync operation. &Q6 Selects asynchronous operation in normal mode. &Rn - RTS/CTS Option &R0 In sync mode, CTS tracks the state of RTS. &R1 In sync mode, CTS is always ON . &Sn - DSR Override &S0 DSR will remain ON at all times. &S1 DSR will become active after answer tone has been detected and inactive after the carrier has been lost. &V - Display Current Configuration and Stored Profiles. &Wn - Store Current Configuration &W0 Store the current configuration as profile 0. &W1 Store the current configuration as profile 1. &Yn - Designate a Default Reset Profile &Y0 The modem will use profile 0. &Y1 The modem will use profile 1. \Nn - Operating Mode \N0 Selects normal speed buffered mode. \N1 Serial interface selected \N2 Selects reliable (error-correction) mode. \N3 Selects auto reliable mode. \N4 Selects LAPM error-correction mode. \N5 Selects MNP error-correction mode. %C - Enable/Disable Data Compression %C0 Disables data compression. %C1 Enables MNP 5 data compression negotiation. %C2 Enables V.42 bis data compression. %C3 Enables both V.42 bis and MNP 5 data compression. S0 - Number of Rings to Auto-Answer S1 - Ring Counter S2 - Escape Character S3 - Carriage Return Character S4 - Line Feed Character S5 - Backspace Character S6 - Wait Time for Dial Tone Before Blind Dialing. S7 - Wait Time For Carrier After Dial S8 - Pause Time For Dial Delay S9 - Carrier Detect Response Time S10 - Lost Carrier To Hang Up Delay S11 - DTMF Tone Duration S12 - Escape Code Guard Time S13 - Reserved S14 - General Bit Mapped Options S15 - Reserved S16 - General Bit Mapped Test Options S17 - Reserved S18 - Test Timer S19 - AutoSync Registers S21 - V.21/General Bit Mapped Options S22 - Speaker/Results Bit Mapped Options S23 - General Bit Mapped Options S24 - Sleep Inactivity Timer S25 - Delay To DTR S26 - RTS to CTS Delay S27 - Bit Mapped Option S28 - Bit Mapped Options S29 - Flash Dial Modifier Time S30 - Disconnect Inactivity Timer S31 - Bit Mapped Options S32 - XON Character S33 - XOFF Character S34-S35 - Reserved S36 - LAPM Failure Control S37 - Desired Line Connection Speed S38 - Delay Before Forced Hang Up S39 - Flow Control S40 - General Bit Mapped Options S41 - General Bit Mapped Options S46 - Data Compression Control S46=136 Execute error correction protocol with no compression. S46=138 Execute error correction protocol with compression. S48 - V.42 Negotiation Action