Hayes Command Reference Edited by Don Hinds NOTE: Not all commands apply to all Hayes modems. Many commands below are for Optima modems only, Some are for voice modems etc. AT commands are issued from the modem's command state in the following format. Command Prefix - AT The AT prefixes the command line to get the modem's attention, detect the speed at which the computer is sending information to the serial port, and recognize the character format (way the information is structured). Commands and Parameters: Escape Sequence - +++ The escape sequence returns the modem to the command state from the on-line state. The escape sequence is issued on a line by itself and is sent without the AT prefix and the [Enter] command line terminator. The escape sequence includes a guard time bracketing the three characters. Both the character used and the duration of the guard time can be changed, if desired, by writing to S-Registers 2 and 12, respectively. AT COMMAND SUMMARY: Command options listed in bold type are those preselected in memory as part of the modem's factory configuration. These options are referred to as factory settings. COMMAND DESCRIPTION ------- ------------ A Enter answer mode; go off hook, attempt to answer incoming call, and go on-line with another modem A/ Re-execute previous command line; not preceded by AT nor followed by [Enter] BO Initiate calls using V.22 at 1200 bps B1 Initiate calls using 212A at 1200 bps B2 If originating a call using V.23, transmit at 75 bps and receive at 1200 bps. If answering and NO selected, transmit at 1200 bps and receive at 75 bps. B3 If originating a call using V.23, transmit at 1200 bps and receive at 75 bps. If answering and NO selected, transmit at 75 bps and receive at 1200 bps. B4 V.23 1200/75 split speed B5 V.23 1200 half duplex B6 V.26bis 1200 (HDX) B10 V.23 split speed 1200/75 B11 V.23 split speed 600/75 B15 Initiate calls using V.21 at 300 bps B16 Initiate calls using 103 at 300 bps B20 V.23 ASB r600/t75 B21 V.23 ASB t600/r75 B22 V.23 split speed t600/r75 B23 V.23 split speed r600/t75 B30 V.22bis (2400) B32 V.26bis (2400) HDX B33 V.34 (2400) B41 Initiate a call using V.32 at 4800 bps B42 Initiate a call using ping pong (half duplex) at 4800 bps B43 IS208 (4800) HDX B44 V.34 (4800) B52 V.32bis (7200) B53 V.34 (7200) B60 Initiate a call using V.32 at 9600 bps B61 Initiate a call using ping pong (half duplex) at 9600 bps B65 V.34 (9600) D Enter originate mode; go off hook, Dial and attempt to go on-line with another modem Parameters 0-9*#ABCD Specifies letters, numbers, and symbols the modem will use when dialing T Dials using Tone method P Dials using Pulse method , Pauses before continuing W Waits for second dial tone @ Waits for quiet answer ! Issues timed break recall (flash) R Places call in reverse mode (to call an originate-only modem) ; Returns to command state after dialing and maintains the connection S=n Dials phone number n (0-3) stored with &Zn=x E0 Do not echo characters from the keyboard to the screen in command state E1 Echo characters from the keyboard to the screen in command state H0 Hang up and place modem in command state H1 Go off hook and operate auxiliary relay I0 Display product code (3-digit number) I1 Calculate ROM checksum (3-digit number) I2 Verify ROM checksum of modem (OK or ERROR) I7 Version number, model # etc I9 PnP ID I12 Display GCP version strings L0-L1 Set low speaker volume L2 Set medium speaker volume L3 Set high speaker volume M0 Turn speaker off M1 Turn speaker on until carrier detected M2 Turn speaker on M3 Turn speaker on until carrier, except during dialing M4 Speaker off, call progress sent to DTE N0 When originating or answering, handshake only at speed specified by S37 and Bn N1 When originating, permit negotiation of a common communication standard at highest associated line speed supported by both modems. Begin negotiations from the DCE line speed specified in S37, falling back to a lower speed if necessary. When answering, fall back from V.32 or V.32 ping pong (half duplex) to V.22/212A/V.22bis, then V.21/103 N2 same as N1 N3 When originating, handshake only at speed specified by S37. When answering, fall back from V.32 or V.32 ping pong (half duplex) to V.22/212A/V.22bis, then V.21/103 N4 same as N3 N5 When originating, permit negotiation of a common communication standard at highest associated line speed supported by both modems. Begin negotiations from DCE line speed specified in S37, falling back to a lower speed if necessary. When answering, handshake only at speed specified by S37 O0 Go to on-line state O1 Go to on-line state, initiate retrain O3 When online, initiate a re-negotaion Q0 Return result codes Q1 Do not return result codes Q2 Return result codes in originate mode, do not return result codes in answer mode Sr? Read and respond with current value of register r (r=number of register; ? requests value) Sr=n Set the value of register r to n (n=value within range of register r) V0 Display result codes as numbers V1 Display result codes as words W0 Do not return negotiation progress messages W1 Return negotiation progress messages W2 Do not return negotiation progress messages; return CONNECT messages using modem-to-modem (DCE) speeds instead of modem-to-DTE speeds X0 Connect X1 Connect nnn (nnn = speed) X2 Connect nnn, Dialtone X3 Connect nnn, Busy X4 Connect nnn, Dialtone, Busy Y0 Do not disconnect for a 1.6 (or longer) continuos break Y1 Disconnect for longspace 1.6 (or longer) continuos break Z0 Reset and recall stored user profile 0 Z1 Reset and recall stored user profile 1 &A0 Autoanswer in answer mode (when S0= is set &A1 Autoanswer in originate mode to autoanswer) &C0 Presume presence of carrier detect signal &C1 Track the status of carrier detect signal &C2 Presume presence of carrier detect signal until on-line, then track status of signal &D0 Ignore the status of DTR signal &D1 Monitor DTR signal. When an on-to-off transition of DTR signal occurs, the modem enters command state. Return to the on-line state (if the connection has not been broken) when the O0 command is issued. &D2 Monitor DTR signal. When an on-to-off transition of DTR signal occurs, hang up and enter the command state &D3 Monitor DTR signal. When an on-to-off transition of DTR signal occurs, hang up and perform a reset &F Recall factory configuration as active configuration &G0 Use no guard tones &G2 Use 1800 Hz guard tones &H0 Disable call-waiting &H1 Enable with one tone &H2 Enable with both tones &H3 Enable with loop disconnect detection &H4 Enable with all loop disconnects detected &J0 Configure for RJ-11, RJ-41S, RJ-45S telco jacks (2nd jack relay never closed) &J1 Configure for RJ-12, RJ-13 telco jacks (2nd jack relay closed when off-hook) FOR JACK SETTING WHEN CONFIGURED FOR MI/MIC SEE REGISTER S-92 &K0 Disable local flow control &K1 Enable RTS/CTS local flow control &K2 Enable XON/XOFF local flow control &K3 Enable RTS/CTS local flow control &K4 Enable XON/XOFF local flow control &K5 Enable transparent XON/XOFF local flow control &K6 Enable unidirectional Xon/Xoff &L0 Configure for dial-up operation &L1 Select 2-wire leased line operation &L2 Select 4-wire leased line operation &On Enter X.25 PAD command state of channel n (0-4) from AT command state &P0 Normal US pulse dialing &P1 Special make/break time #1 &P2 Special make/break time #2 &Q0 Communicate in async direct mode, DTE must match DCE &Q1 Communicate in synchronous mode 1 - Async-to-Sync &Q2 Communicate in synchronous mode 2 - Stored Number Dial &Q3 Communicate in synchronous mode 3 - Voice/Data Switch &Q4 Communicate in synchronous mode 4 - Hayes AutoSync &Q5 Communicate in async error-control mode with buffering &Q6 Communicate in async mode for interfaces requiring constant speed between the DTE (computer/terminal) & DCE (modem) &Q8 MNP error control &Q9 V.42bis error control/compression &Q10 X.25 error control &R0 Track CTS according to RTS &R1 Assume presence of CTS, ignore RTS &S0 Assert DSR signal always &S1 Assert DSR signal prior to handshake operation &S2 Assert DSR signal after handshake negotiation, but before CONNECT nnn result code sent to DTE NOTE: &T settings are NOT USER settings. &T0 Terminate test in progress &T1 Initiate local analog loopback &T3 Initiate local digital loopback &T4 Grant request from remote modem for remote digital loopback &T5 Deny request from remote modem for remote digital loopback &T6 Initiate remote digital loopback &T7 Initiate remote digital loopback with self test &T8 Initiate local analog loopback with self test The &T commands must be entered when the modem is configured for &Q0. &U0 Enable trellis coding (V.32 9600 bps only) &U1 Disable trellis coding &V View active configuration, user profiles, and stored telephone numbers &V6 View Blacklist (where applicable) &V8 View Call statistics &W0 Write storable parameters of current configuration in memory as profile 0 &W1 Write storable parameters of current configuration in memory as profile 1 &X0 Derive transmit clock signal from modem's internal oscillator (internal clock signal on pin 15) &X1 Derive transmit clock signal from attached computer (external clock signal on pin 24) &X2 Derive transmit clock signal from receive carrier (slave receive clock signal on pin 15) &Y0 Specify stored user profile 0 as power-up configuration &Y1 Specify stored user profile 1 as power-up configuration &Zn=x Store phone number x in location n (0-3) S-REGISTER SUMMARY: FACTORY REGISTER DESCRIPTION RANGE/UNITS SETTING -------- ----------- ----------- ------- S0 Select ring to answer on 0-255 rings 0 S1 Ring count 0-255 rings 0+ S2 Escape sequence character 0-127 ASCII 43 S3 Carriage return character 0-127 ASCII 13+ S4 Line feed character 0-127 ASCII 10+ S5 Back space character 0-32, 127 ASCII 8+ S6 Wait before blind dialing 2-255 sec 2 S7 Wait time for carrier 1-255 sec 50 S8 Duration of comma delay 0-255 2 S9 Carrier detect response time 1-255 1/10 sec 6 S10 Delay carrier loss to hangup 1-255 1/10 sec 14 S11 DTMF dialing speed 50-255 msec 95 S12 Escape sequence guard time 0-255 1/50 sec 50 S18 Select test timer 0-255 sec 0 S25 DTR change detect time 0-255 1/100 sec 5 S26 RTS/CTS delay 0-255 1/100 sec 1 S30 Automatic timeout. 0-255 10 sec 0 S31 ASCII XON character 0-255 17 S32 ASCII XOFF character 0-255 19 REGISTER S36: Negotiation fallback - 0 Hang up 1 Attempt a standard asynchronous connection (&Q0) 3 Attempt an asynchronous connection using automatic speed buffering (&Q6) 4 Attempt a V.42 Alternative Protocol connection (MNP compatible); if negotiation fails, hang up 5 Attempt a V.42 Atlernative Protocol connection (MNP compatible); if negotiation fails, attempt a standard asynchronous connection 7 Attempt a V.42 Alternative Protocol connection (MNP compatible); if negotiation fails, attempt an asynchronous connection using automatic speed buffering NOTE: The selected fallback option can be initiated immediately with Register S48. For example, a connection attempt using the Alternative Protocol can be forced by setting S48=128 and S36=5 or 7. REGISTER S37: Maximum DCE line speed - selects the speed (for all modes except V.25bis) VALUE EXPLANATION ----- ----------- 0 Speed of last AT Command issued 1 75 bps 2 110 bps 3 300 bps 5 1200 bps 6 2400 bps 7 4800 bps 9 9600 bps 10 12000 bps 11 14400 bps 26 16800 bps 12 19200 bps 33 21600 bps 29 24000 bps 34 26400 bps 15 28800 bps REGISTER S38: Delay before forced hang up 0-255 seconds (default 20) REGISTER S39: Flow control setting 0 none 1 RTS/CTS 2 XON/XOFF 3 RTS/CTS 4 XON/XOFF 5 Transparent XON/OFF 6 Unidirectional XON/XOFF REGISTER S44: Framing technique 2,3 REGISTER S46: Error-control protocol selection - 0 Either LAPM or fallback to LAPB 1 LAPB only 2 LAPM or fallback to LAPB; use data compression+ 3 LAPB with data compression+ 6 X.25 or fallback to LAPB; use data compression+ 136 LAPM only 138 LAPM with data compression+ 134 X.25 REGISTER S48: Feature negotiation action - selects how feature negotiation is used when making connections with the remote system. 0 Negotiation disabled; presume the remote modem is configured for and has the capabilities necessary for the connection selected with S46 3 Negotiation enabled, but originating modem remains silent during detection phase for connections with MNP modems; defeats connection sequence with other V.42 modems 7 Negotiation enabled 128 Negotiation disabled; forces fallback options specified in S36 to be taken immediately REGISTER S49: Buffer lower limit -. The range is 1-249 bytes; the factory setting is 8. REGISTER S50 : Buffer upper limit - The range is 2-250 bytes; the factory setting is 16. REGISTER S55: Autostream protocol level 0-5 REGISTER S57: Network options for X.25 packet 0,1,2,3 REGISTER S59: Leased line failure alarm. 0-off 1-on REGISTER S60: Leased line failure action 0-idle 1-see S61 REGISTER S61: Leased Line retry 0-indefinite 1-255 retry ‘n’ times REGISTER S62: Leased Line Restoral 0- does not attempt leased line restoral 1-60 retries leased line after ‘n’ minutes. REGISTER S63: Leased Line Transmit level 0-15 in dBm, default 0 REGISTER S64: Leased Line Receive level 0-highest 2-2nd range 3-3rd range REGISTER S69: Link layer window size - sets the number of frames (packets) sent between acknowledgements from the remote system. The range is 1-15 with a factory setting of 15. LAPM connections use a window size of 1-15; LAPB connections and X.25 connections use a window size of 1-8. If a LAPB or X.25 connection is made, any value greater than 8 is treated as 8. REGISTER S70: Maximum number of retransmissions - determines how many times the modem will retransmit a frame. The range is 0-255 retries with a factory setting of 10. REGISTER S71: Link layer timeout - sets the delay between retransmissions to the remote system. The range is 1-255 1/10 seconds, with a factory setting of 2 (200 milliseconds). REGISTER S72: Loss of "flag idle" timeout - specifies the interval between idle flags. The range is 1-255 seconds with a factory setting of 30. REGISTER S73: No activity timeout - specifies the period of inactivity (no data, only good carrier and flag idle received) before the modem sends a query (an "RR") to the remote modem to verify that it is operating properly. The range is 1-255 seconds with a factory setting of 5. REGISTERS S74-S81 X.25 options REGISTERS S84-S85 ASU options REGISTER S86: Connection failure cause code - helps determine the cause of a connection failure. When the modem issues a NO CARRIER result code, a value is written to this S-Register. To read this register following the connection failure, issue ATS86 [Enter]. The modem will report one of the values below. 0 Normal hang up; no error occurred 4 Physical carrier loss 5 Feature negotiation failed to detect presence of another error-control modem at the other end 6 Other error-control modem did not respond to feature negotiation message sent by this modem 7 Other modem is synchronous-only; this modem is asynchronous-only 8 Modems could not find a common framing technique 9 Modems could not find a protocol in common 10 Incorrect Feature negotiation message sent by other modem 11 Synchronous information (data or flags) not received from other modem. Modem waited 30 seconds before hanging up 12 Normal disconnect initiated by other modem 13 Other modem did not respond after many transmissions of the same message. Modem made 10 attempts then hung up 14 Protocol violation occurred 15 Compression failure 16 Speed in S37 did not match speeds in S109 17 S116 timeout 18 Timer S30 caused hangup 19 Long Space disconnect 20 X.25 network rejected offered X.32 ID 21 X.25 network uses different security option REGISTER S87: Fixed DTE – default high AT speed 25 -12000 13 -14400 14 -19200 15 -28800 28 -38400 18 -57600 31 -155200 65 -230400 REGISTER S89: Sleep mode timer for low power modems 0-255 seconds, default 10 REGISTER S91: Dial up line transmit level 0-15 dBm, default 10 REGISTER S92: MI/MIC operation - VALUE EXPLANATION ----- ----------- 0 MI/MIC disabled 1 level triggered, originate mode, RI pulse enabled 3 edge triggered, originate mode, RI pulse enabled 5 level triggered, answer mode, RI pulse enabled 7 edge triggered, answer mode, RI pulse enabled 9 level triggered, orginate mode, RI pulse disabled 11 edge triggered, originate mode, RI pulse disabled 13 level triggered, answer mode, RI pulse disabled 15 edge triggered, answer mode, RI pulse disabled REGISTER S93: V.25bis DTE interface speed VALUE EXPLANATION ----- ----------- 3 300 bps 5 1200 bps 6 2400 bps 7 4800 bps 9 9600 bps REGISTER S94: Command mode selector - provides an alternative to setting internal DIP switches VALUE EXPLANATION ----- ----------- 0 Standard AT command operation (factory setting) 1 Asynchronous V.25bis using addressed access 2 Synchronous V.25bis (HDLC) using addressed access 3 Synchronous V.25bis (Character framing) using addressed access 5 Asynchronous V.25bis using direct access 6 Synchronous V.25bis (HDLC framing) using direct access 7 Synchronous V.25bis (Character framing) using direct access 9 Asynchronous V.25bis using addressed access with EBCDIC character set option 10 Synchronous V.25bis (DHLC) using addressed access with EBCDIC character set option 11 Synchronous V.25bis (Character framing) using addressed access with EBCDIC character set option 13 Asynchronous V.25bis using direct access with EBCDIC character set option 14 Synchronous V.25bis (HDLC framing) using direct access with EBCDIC character set option 15 Synchronous V.25bis (Character framing) using direct access with EBCDIC character set option REGISTER S95: Negotiation message options - BIT VALUE EXPLANATION --- ----- ----------- 0 1 Use speed of DTE-to-modem connection 1 2 Append "/ARQ" to CONNECT result code when an error-control connection is made 2 4 Enable CARRIER messages 3 8 Enable PROTOCOL messages 4 16 Enable AUTOSTREAM messages 5 32 Enable COMPRESSION messages