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CHAPTER 1

INTRODUCTION
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     Congratulations on your purchasing of this 56-kbps Modem, X2TM U.S. 
     Robotics Technology data transmission mode. The modem provides you 
     complete functions for the following modes: Group 3 Fax, data, 
     V.42/MNP 2-4, and V.42 bps/MNP 5. Additionally, the modem provides 
     special modes of operation for VoiceView, power managerment, and 
     loopback testing. In data mode, the modem operates at up to 33600 
     bps (send) and up to56,000 bps (receive). The x2 Technology data 
     receive rates of up to 56,000 bps can be achieved only in connections 
     with equipment-compatible ISPs (Internet Services Providers).

     This manual describes how to install and operate the modem.

1.1 The Modem Family

  TYPE                         DESCRIPTION
---------------------------------------------------------------------------------------------------------------
 EXTERNAL MODEM

 x2 56K-bps         The modem feature With a complete industry standard
                    for data, fax and voice applications, full duplex ,
                    echo-cancelled digital speakerphone ITU-V.80 
                    videoconferencing

                    - International telephony support

 INTERNAL MODEM

 x2 56K-bps         It has the same features as the external modem with
                    the extended ISA bus interface with a built- in 
                    highspeed UART 16550, COM port selectable from COM 1 
                    to COM4 with IRQ setting at any of the IRQ3, 4, 5 7,
                    10, 11or 12. It also can operate in Plug and Play mode
                    for Window 95.

2 Basic Features

  The modem has the following basic features:
 [] Supported Communication Mode and Data Rate
     U.S. Robotics(R) 56kbps x2f" Technology 
     V.34 + (33,600, 31,200, 28,800, 26,400, 24,000, 21,600, 19,200, 
     16,800, 14,400, 12,000, 9600, 7200, 4800 and 2400bps) 
     V.32bis (14,400, 12,000, 9600, 7200 and 4800bps)
     V.32 (9600 and 4800bps)
     V.22bis (2400 and 1200bps)
     V.22 (1200bps) V.23 (1200/75) 
     V.21 (300bps) 
     BELL 212A (1200bps) 
     BELL 103 (300bps)

 [] Supported Fax Mode and Data Rate 
     V.17 (14,400, 12,000, 9600 and 7200bps)
     V.29 (9,600, 7,200 and 4,800bps) 
     V.27ter (4800 and 2400bps)
     V.21 Channel 2 (300bps)
     Implement a standard fax mode AT command set compatible with any 
     communication software that supports EIA/TIA-578 Class 1 standards.

 [] Error Correction and Data Compression 
     MNP Class 2 to 5 
     V.42 and V.42bis

 [] Operating Mode
     Asynchronous mode (available DTE baud rate at 115,200, 57,600, 38,400
     , 19,200, 9600, 4800, 2400, 1200 and 300) in any of the data format :
     8+ No parity, 7+ Even parity, 7+ Odd parity, 7 + Space, 7 + Mark or 
     7+ No parity.
     The modem will auto detect the baud rate and data format.

 [] Line Operating Mode
     Dial up line operation
     DTMF or Pulse dialing modes 
     Direct Access Arangement (DAA) to the telephone line
     Call Progress Tone detection (Dial tone, Busy and Ring back signals)

 []  Voice Mode 
     Supports telephone emulation mode, IS-101 voice commands, and record 
     and play back message capabilities.
     Allows a microphone-speaker and the modem to be used as a complete
     telephone.

 []  Power Management Modes
     The modem provides both sleep and stop modes to reduce power
     consumption when the modem is inactive.

 []  ISA Bus Interface with Plug and Play mode (Internal Modem Only)
     Supports extended ISA bus interface with seven IRQs (IRQ 3, 4, 5, 7, 
     10,11and 12) available.
     COM port is Selectable from COM1 to COM4 
     Emulates the electrical and register functions of 16C550A and 16C450
     UARTs.
     Build inside Plug and Play function for Window95.


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CHAPTER 2
COMMANDS
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2.1 General Command Information

     This chapter provides an alphabetized reference with examples for all
     commands for the modem.

     More than one command can be placed on a single command line and, 
     if desired, seperated with spaces for readability. Once the Carriage
     Return (Enter) key is pressed, the command line is executed except 
     the A/ command which can be executed without entering the carriage 
     return key.

     The modem accepts either upper or lower case characters in the 
     command line and ignores any spaces within or between commands. 
     Typing errors can be corrected with the Backspace key.

2.2 AT Command Reference

     AT       Command Prefix
---------------------------------------------------------------------------------------------------------------
     Every time you give a command string to the modem, you must type AT 
     (Attention) prefix at the beginning of the command string. These two 
     characters can be typed in upper- or lower-case letters. When you
     type AT and press ENTER, you will get an OK response from your modem 
     immediately. The modem analyses the command prefix and detects the
     baud rate and data format of your computer.


     A/  or  al   Repeat Last Command
---------------------------------------------------------------------------------------------------------------
     This command re-executes the last AT command line stored in the 
     command buffer. A/ is the only command not preceded by the AT prefix 
     and terminated by carriage return.


     A         Answer Command
---------------------------------------------------------------------------------------------------------------
     The Answer command places the modem OFF-HOOK immediately, sends an 
     answer tone, sets the modem in answer mode, and waits for a remote 
     carrier regardless of the content of register SO. If a specified time
     determined by S7 is met and the modem still can not establish a 
     connection with a remote modem, the modem goes ON-HOOK and 
     disconnected from the line. The modem will also drop the line and 
     send a NO CARRIER result code to your compuer. if you enter any 
     character before the modem connect with the remote side or the modem
     can not connect with the remote modem within the time specified by 
     S7. The modem will not execute any command after the A command.
     Example,
     Enter:      ATA 
     Modem:      Goes OFF-HOOK, sends answer tone, and waits for the 
                 remote side to respond to its carrier.


     B          Select BELL or CCITT
---------------------------------------------------------------------------------------------------------------
     The B command is used to determine the auto mode fall back sequence.
     The parameter followed by the B command will determine which protocol
     was selected:

     B0 = Select CCITT operation at 300 or 1200bps during Calling or 
          answering.
     B1 = Select BELL operation at 300 or 1200bps during calling or 
          answering.
     B2 = Select CCITT V.23 modulation connection only, the modem will not
          connect for any other speed or modulation. The originating modem
          transmits at 75bps and receive at 1200bps, the answering modem 
          transmit at 1200bps and receives at 75bps. 
     B3 = Selects CCITT V.23 modulation connections only. The originating 
          modem transmit at 1200bps and receives at 75bps, the answering 
          modem transmits at 75bps and receives at 1200bps.


     Cn       Carrier Control
--------------------------------------------------------------------------------------------------------------- 
     This command is reserved for selecting between controlled carrier or 
     constant carrier modes. The modem supported only constant carrier
     mode.
     n=O Transmit carrier always off (returns an ERROR message) 
     n=l  Normal transmit carrier


     D           Dial Command
---------------------------------------------------------------------------------------------------------------
     The D command places the modem OFF-HOOK immediately, and dials
     according to the string entered and attempts to establish a 
     connection. If no dial string is supplied, the modem will go off-hook
     and attempt the handshake in originate mode. This command will be 
     aborted upon receipt of any DTE character. If the modem has not 
     finished dialing, a NO CARRIER response code will result.

     If +FCLASS =O is selected before the dialing command, the modem will 
     behaves like a data modem and will attempt to connect to another data
     modem. The modem will wait upto the period of time specified by S7
     for the carrier and complete the handshake. If this time expires
     before the modem completes the handshake, the modem goes ON-HOOK with
     a NO CARRIER response and returns to command mode.lf the modem's in 
     fax operation and + FCLASS = 1 is issued, the modem attempts to 
     connect to a FAX machine( or fax modem).

     The D command can be followed with sub-commands or parameters, the 
     valid dial string parameters are described below:

     0-9         DTMF or PULSE digit 
     A-D         DTMF digits
     *           The DTMF 'star' digit
     #           The 'gate' digit for DTMF only
     T           Touch - Tone dial (DTMF)
     P           Pulse dial
     R           Reverse mode, after dialing place the modem in answer 
                 mode.
     W           Wait for dial tone before processing the next symbol in 
                 the dialing string. The dial tone waiting time is
                 specified by the S6 register. If a Busy signal is 
                 detected, the modem responds to the computer with a BUSY
                 response code and then goes into off-line command mode.
     !           HooMlash, Commonly used with PBX system, the modem will 
                 go ON-HOOK for 0.5 seconds.
     ;           Return to command mode after dialing
     ,           Dial pause: tthe modem will pause for a time specified by
                 S8 before dialing the digits that follow.
     S=n         Causes the modem to dial a telephone number previously 
                 stored in the non-volatile memory with the AT&Zn = x
                 command. (n = O to 3)
     to walt for specified amount of time 
     (S7) followed by 5 seconds of silence before processing 
     the next dial modifier. If the modem does not detect the 5 
     seconds of silence before the expiration of the call abort 
     time specified by S7, the modem will terminate the call and 
     respond with a NO ANSWER message. 
     Example,
     Enter:       AT DT 9,(00261) 9 275 7900 
     Modem:       The modem will use DTMF to dial the number. The first 
                  digit 9 will be dialed and wait for the pause time 
                  specified by S8, then the rest of the digits will be
                  dialed. The bracket on the above command string has no
                  influence or the operation which is used to format the 
                  dial string.


     E       ECHO COMMAND
---------------------------------------------------------------------------------------------------------------
     The echo command determines whether the modem will echo the command 
     characters to your computer or terminal. The El command causes the 
     modem to echo back all the characters received in command mode, and 
     the EO command will disable the echo function.

     The E1 command lets you verify that the command string you have sent 
     is correct. Use the EO command when your computer is in half duplex 
     mode. Otherwise the characters will appear twice on your computer
     screen.

     Example,  
     Enter:       ATE1
     Modem:       After this command, the modem will echo all characters
                  that you send from your computer or terminal.
     Enter:       ATEO 
     Modem:       The modem will not echo any characters sent from your 
                  computer.


     H       ON/OFF HOOK COMMAND
---------------------------------------------------------------------------------------------------------------
     The H command controls the hook inside the modem. When H1 command is
     issued, the modem goes off-hook. The HO command causes the modem goes
     on-hook.


     I       IDENTIFICATIONS/CHECKSUM OPTION 
---------------------------------------------------------------------------------------------------------------
     The I command will cause the modem responses the manfacturer
     identifications or the checksum verify status. 
     I0     Request the modem to send product code. 
     I1     Request the firmware version of the modem.
     I2     Verify ROM checksum.
     I3     Request the modem to send its device set name.
     I4     Reserved 
     I5     Reserved for modem chip hardware configuration 
     I6     Report the country code
            US= United States 
            JP= Japan 
            UK= United Kingdom
            GR = Germany 
            FR = France
            IT= Italy 
            NT= Netherlands 
     I7     Board manufacturer firmware version 
     I8     Modem firmware features

            Bit O          O = No VoiceView
                           1 = VoiceView supported 
            Bit 1          O = No DSVD 
                           1 = DSVD supported
            Bit 2-7        Reserved

     I10    Reques the hardware configuration of the modem:

            Bit            2 1 0
                           O O O      Telephone-Emulation Mode 
                           1 O O         Digital speakerphone (+ VSP = n)
            Bit3           O = No Caller ID
                           1 = Caller ID hardware on board
            Bit4           Reserved
            Bit5           O = Device does not support Plug and Play 
                           1 = Plug and Play supported by device
            Bit6           O = Microcontroller firmware in EPROM 
                           1 = Microcontroller firmware in FLASH
            Bit7           Reserved 


     L - Speaker Volume Control 
---------------------------------------------------------------------------------------------------------------
     Select the volume of the speaker.
     LO    Select the lowest speaker volume. 
     L1    Select the lowest speaker volume. 
     L2    select medium speakervolume.
     L3    Select the highest speakervolume.


     M - Speaker Control
---------------------------------------------------------------------------------------------------------------
     There are four parameters for the M command:
     MO    Speaker always off.
     M1    Speaker ON until carrier signal detected. 
     M2    Speaker always ON even in data mode.
     M3    Disable the speaker while the modem is recehring a carrier 
           signal from remote station and while the modem is dialing.


     Nn        Select Data Rate Handshake
---------------------------------------------------------------------------------------------------------------
     This command specifies whether tht: resulting modem-to modem 
     modulation can be different from the !nodulation specified in the 
     + MS = m i carrier > parameter.
     NO    When originating or answering, connect only at the data rate 
           specified by the modulation.
     N1    When originating or answering, begin handshaking at the 
           modulation data rate. If the remote modem does not support the
           specified modulation data rate, fall down to the highest
           compatible data rate.


      O         ON-LINE COMMAND
---------------------------------------------------------------------------------------------------------------
      O0   Enters on-line data mode without retrain. 
      O1   Enter on-line data mode with retrain.
      The O command is used to return the modem to the data mode, after
      temporarily bringing it to the command mode by using the escape 
      sequence (+ + +). The ATO or ATO0 causes the modem return to the 
      data mode and response with CONNECT XXXX. The O1 command causes the
      modem return to the data mode and initiate an equalizer retrain 
      sequence. When the modem receives too much error due to the loss of
      equalization, the O1 command may be used to reduce the error. 
      However, if the errors are caused by other reason, issuing the 
      command O1 will not improve the receiveperformance. The O1 command 
      is only valid for the modem connected at 2400bps(V.22bis) or higher 
      speed (V.34A/V.32bis/V.32). For V.34/V.32bis/V.32 communication, the
      modem will automatically checking the received mean square error and
      determine whether it is necessary to retarining itself or not.

      Q        QUIET COMMAND 
---------------------------------------------------------------------------------------------------------------
      The Q command enables or disables responses from the modem. The
      command Q0 enables the responses to be sent by the modem. When set
      to Q1, the modem will not generate the responses. The command does 
      not influence the responses when you request the content of S 
      register, the identification code, checksum result, and the results
      of modem diagnostics.

      Example: 
      Enter:       ATQ0
      Modem:       OK
      Enter:       ATQ1
      Modem:       (no response)
      Enter:       ATQ1S0?
      Modem:       000

      Issuing the Q1 and get no response from your modem is not meaning
      your modem does not execute the commands.


      Sr?         READ A REGISTER'S VALUE
---------------------------------------------------------------------------------------------------------------
      This command returns the decimal value of the S register.

      Example:     
      Enter:       ATS7?
      Modem:       030
                   OK
      You may also read multiple S register at a time.

      Example: 
      Enter:       ATS7? S0?
      Modem:       030 
                   000 
                   OK


      Sr=n     SETS REGISTER VALUE 
---------------------------------------------------------------------------------------------------------------
      This command writes a decimal number 'n' to S-register 'r'.

      Example:
      Enter:      ATS7=6O 
      Modem:      OK
      Enter:      ATS7=6OSO=1 
      Modem:      OK


      V        SELECT VERBAL OR NUMMERICRES RESPONSES
---------------------------------------------------------------------------------------------------------------
      The V command selects the type of responses returned by the modem 
      after or during execution of commands. V1 selects VERBAL responses
      and V0 or V selects nummeric responses.

      Example,
      Enter:      ATV1 
      Modem:      OK
      Enter:      ATV0
      Modem:      0


      W         Connect Message Control
---------------------------------------------------------------------------------------------------------------
      This command selects whether the modem sends to the computer 
      independent modem connection result codes for speed, error control
      protocol, or data compression.

      W0    Upon connection, the modem reports only the DTE speed.
            Subsequent responses are disabled.
      W1    Upon connection, the modem reports only the DTE speed.
            Subsequent responses are disabled.
      W2    Upon connection, the modem reports the line speed, the error 
            correction protocol, and the DTE speed, respectively.
            Subsquent responsesare disabled.
      W3    Upon connection, the modem reports the DTE data rate,
            modulation mode, error correction, data compression, DCE
            transmitter speed and DCE receiver speed.
            Modulation types include: V21, V22, V22B, V23C, V32, V32B and
            V34.
            Error correction types include: NONE, LAPM, MNP Data 
            compression types include: NONE, V42B, MNPS The response codes
            follow the following format:

            CONNECT (DTE data rate)/(modulation)/(error correction)/ (data
            compression)/TX = (DCE transmit data rate)/
            RX = (DCE receive data rate)

      Example: (After connection with remote modem) 
      Modem: CONNECT 1 1 5200/V34/LAPM/V42B/TX = 33600/RX = 33600


      X        BASIC OR EXTENDED RESPONSE CODE
---------------------------------------------------------------------------------------------------------------
      The purpose of the X command allows you to select the basic result 
      code set or the extended result code set (mentioned in Chapter 4), 
      and to control the modem to meet the specifications of your 
      telephone system. The default setting is X0, which means that the
      modem only uses the basic result code set -- never displays CONNECT
      2400 or CONNECT 1200. Once you send Xl, X2, X3 or X4 commands to the
      modem, it will tell you at what speed it is connected. When your 
      modem connect at 2400bps, you will get a CONNECT 2400 message or 
      CONNECT 1200 when the modem connects at 1200bps.

      The X2 command allows your modem to detect the dial-tone signal 
      before dialing. When entering this command, followed by a dialing 
      string, the modem goes off hook and waits for a dial-tone signal. If
      a dial-tone signal is present, then the modem starts to dial the 
      telephone number If "Ot, then a NO DIALTONE message is displayed.

      The X3 command causes the modem to detect BUSY TONE instead of dial 
      tone. when you issue the X3 command to the modem, followed by ,
      telephone number, the modem will check the line condition after
      dialing. If a busy signal is detected, then the modem returns a BUSY
      message and goes on-hook immediately If not, then the modem keeps 
      waiting for a carrier signal until thetime set in register S7 has 
      elapsed.

      The X4 command lets you not only detect a dial-tone signal but also
      check the busy signal after dialing.

      The combination of X commands allows you to adjust the modem to meet
      the requirements of yourtelephone system In some areas, the 
      telephone system does not provide a stable dial-tone signal. Under
      these conditions, you' modem will not detect the dial tone correctly.
     
      When error correctionor data compression is activated, the X1, X2, 
      X3 and X4 command is recommanded.


---------------------------------------------------------------------------------------------------------------
      YO -- Enable Long Space Disconnect
      Y1 -- Disable Long Space Disconnect (factory setting). 
      When enabled, the modem disconnects (goes ON-HOOK) if it detects at
      least 1.6 seconds BREAK signal from the remote modem.


      Z        RESET
---------------------------------------------------------------------------------------------------------------
      The Z command is a software reset command; any command following 
      Z will be ignored. when the modem receives the this command, the
      modem hangs up, restores the active profile from the non-volatile 
      memory, and then returns OK. The Z0 or Z command will restore the
      profile with the configurationprofile 0 in non-volatile memory and
      the Z1 command will retrieve the configuration profile 1 from 
      non-volatile memory.


      &C       DCD OPTIONS 
---------------------------------------------------------------------------------------------------------------
      The &C command will influence the operation of the RS-232C exchange
      circuit -- DCD in asynchronous mode. The &C0 or &C command will 
      cause the modem maintains DCD always ON and ignores the actual state
      of the data carrier from the remote modem. For the &C1 command,The 
      modem will turn on the DCD only if valid carrier is detected by the
      modem.


      &D       DTR OPTIONS 
---------------------------------------------------------------------------------------------------------------
      This command controls how the modem responds to DTR. 
      &D0  In asynchronous mode (&Q0), the modem ignores DTR. 
      &D1  The modem switches from data mode to command mode when an 
           on-to-off transition of DTR occurs.
      &D2  An on-to-off transition of DTR causes the modem to go on-hook 
           and to disable auto-answer mode. Auto-answer mode (S0 is not
           equal to zero) is enabled when DTR is turned on.
      &D3  An on-to-off transition of DTR re-initializes the modem. The
           re-initialize procedure performs the same function as power-up 
           reset, except that the internal UART registers are not 
           reconfigured.

    
      &F        Load Factory Defaults
---------------------------------------------------------------------------------------------------------------
      This command loads the factory command defaults and S-register
      factory defaults into active configuration.


      &G        GUARD TONE SELECTION
---------------------------------------------------------------------------------------------------------------
      The &G command controls the guardtone. &G0 selects no guard tone. 
      &G1 selects a 550Hz guard tone and &G2 generates a 1800Hz guard tone
      used for international communication. The default setting is &G0.


      &j       TELEPHONE JACK SELECTION
---------------------------------------------------------------------------------------------------------------
      The &J0 or &J1 command controls the jack connection type of the 
      modem. The &J0 will select the standard phone line type, such as 
      RJ11, RJ41 or RJ45S and the &J1 command will select the Multi line
      telephone jack type such as RJ12 or RJ13. This command may be
      totally disabled by the manfacturer due to the difference of the 
      telecommunication regulation in individual area.


      &K       FLOW CONTROL 
---------------------------------------------------------------------------------------------------------------
      This commmand defines the DTE-to-modem flow control mechanism. 
      Software Row control uses the character XOFF (13h) and XON (11h) to 
      stop and to start data transmission, respectively, both to and from
      the DTE. Bidirectional hardware flow control also uses the RTS 
      control to stop/start data from the modem. 
      &KO  Disables flow control.
      &K3  Enables bidirection hardware flow control.
      &K4  Enables XON/XOFF software flow control.


      &P       MAKE AND BREAK RATIO SELECTION
---------------------------------------------------------------------------------------------------------------
      The time interval for the make and break signal of the dialing pulse
      is controlled by this command.
      &P0  Selects 39/61 makelbreak ratio at 10 pulses per second. 
      &P1  Selects 33/67 makelbreak ratio at 10 pulses per second.


      &Q       Select Communication Mode
---------------------------------------------------------------------------------------------------------------
      This command controls whether the modem is operating in asynchronous
      or synchronous mode. This modem only supports asynchronous mode.


      &S       DATA SET READY OPTIONS 
---------------------------------------------------------------------------------------------------------------
      The &S and &S0 commands causes DSR to remain ON all the times while 
      the modem is turned on.
      
      Command &Sl causes the DSR become active after answer tone has been
      detected and inactive after the carrier has been lost.


      &Tn      TEST COMMANDS 
---------------------------------------------------------------------------------------------------------------
      The eight &T commands are listed below.
      &T0 --- Terminates any test currently in progress. Must be the last 
              command in a command string.
      &T1 --- Initiates a Local Analog Loopback test in accorance with 
              CCITT V.54, L3. When this command is issued, the modem hangs
              up. The CONNECT XXXX message is displayed upon the start of
              the test.
      &T3 --- Initiates a Local Digital Loopback. If no connection exists,
              ERROR is returned.
      &T4 --- Setting the modem to grant a request from the remote modem 
              for a Remote Digital Loopback (CCITT V.54, L2). 
      &T5 --- Prohibits the modem from granting a request from the remote
              modem for a Remote Digital Loopback.
      &T6 --- Initiates a Remote Digital Loopback test in accordance with
              CCITT V.54, L2.
      &T7 --- Initiates a Remote Digital Loopback with Selftest. An 
              internal generated alternate dot pattern will transmitted to
              remote modem. An error detector capable to count the number 
              of errors that received.
      &T8 --- Initiates a Local Analog Loopback with Selftest. During 
              testing, an internal generated alternate dot pattern.will
              send at the selected bit rate. Also, an error detector 
              capable to count the numbers of error received.


   &Un       Trellis Coding Control 
---------------------------------------------------------------------------------------------------------------
     This command selects whether the modem transmits or receives 
     modulated 9600bps carrier with QAM or Trellis encoding for V.32. 
     &U0  Enabled (Trellis modulation with QAM modulation as a
          fallback)
     &U1  Disabled (QAM modulation only)


     &V      View Active Profile and Stored Profiles 
---------------------------------------------------------------------------------------------------------------
     The &V command causes the modem sending out the active profile, 
     and the two sets of stored configuration profile to your computer 
     or terminal.


     &w        Store Active Profile
---------------------------------------------------------------------------------------------------------------
     The active configuration settings are maintained in S-registers of
     the system RAM (random access memory). The &W command saves a 
     subset of the S-registers in system nonvolatile memory. These 
     setting are restored automatically whenever the modem is turned 
     on, or issuing the ATZ command.

     &W or &W0 causes the modem write active profile to non-volatile 
     memory as profile O.
     
     &W1 causes the modem write active profile to non-volatile memory 
     as profile 1.


     &Yn       Select Configuration Profile 
---------------------------------------------------------------------------------------------------------------
     The modem will fetch the configuration profile from non-volatile 
     memory when the power is first time applied to the modem. The &Y 
     option will let the modem to determine profile 0 or profile 1 has
     to be fetched from non-volatile memory. The &Y or &Y0 will select
     profile 0 as power on active profile. The &Y1 will select profile
     1 as active profile.


     &Zn=m   
---------------------------------------------------------------------------------------------------------------
     Store Telephone Number Used to store the telephone number in 
     nonvoltaile memory for subsequent dialing using ATDS command. m
     represents an ASCII string composed of dial digits and dial 
     modifier, the n is the telephone number location in non-volatile
     memory which value will from 0 to 3. The modem can store up to 
     four sets of the telephone number for further used. If n>3 or m>25
     digits (including dial modifiers), the ERROR message will return.

     Example:
     Enter:      AT &Z = T 9 W (408) 997 6478 
     modem:      OK 
     Result      Modem stores T9W4089976478 in nonvoltaile memory 
                 telephone set 0.

     The number can then be dialed automatically by issuing the 
     following command:

     Enter:      AT DS0 or ATDS 
     Modem:      T9W4089976478 
     Result      Modem is starting to dial

     Enter:      AT&Z1= T1234567890 
     Modem:      OK
     Result:     Modem will store the dialing command T1234567890 
                 into non-volatile memory telephone number location 1.


     %E         Auto Retrain Control
---------------------------------------------------------------------------------------------------------------
     This command controls whether the modem automatically initiates a
     modem retrain whenever the received data signal quality falls below a
     threshold that may affect data reliability.

     %E0       Disabled
     %E1       Enabled


     &Gn       Rate Renegotiation 
---------------------------------------------------------------------------------------------------------------
    This command selects whether the modem automatically initiates a change
    to a higherspeed or lower speed depending on received signal quality (that
    is, rate negotiation). The modem always responds to any rate change 
    initiated by the remote modem. 
    %G0        Disabled 
    %G1        Enabled  


     &Cn     Generate Data Modem Calling Tone
---------------------------------------------------------------------------------------------------------------
    This command allows the DTE to select whether the modem sends a
    1300Hz calling tone or V.8 calling tone when originating a data modem 
    connection.
    -C0         Calling tone disabled
    -C1         1300Hz calling tone sent for all data modem connection
    -C2         V.8 calling tone sent for V.34 modulation and 1300Hz calling
                    tone sent for all other modulations.


     +MS=m Modulation Selection
---------------------------------------------------------------------------------------------------------------
     This command sets the type of modulation used for the send and receive
      speeds. Setting for Bn, + MS = m, Nn and S37 determine the allowable modem 
     connections. Nn performs the same function as the +MS=m ~automode> parameter. 
     S37 performs the same function as the + MS = m < max rate > parameter.
     For V.34 modulation connections, the modem transmitter can be at one speed and the
     receiver can be at another speed. Thus, there are two types of connection that can take
     place, asymmetrical and symmetrical. An asymmetrical connection occurs when the
     modem's transmitting speed is different from the the receiving speed. A symmetrical 
     connection occurs when the modem's transmitting and receiving speeds are the same.
    The modem can be configured by the + MS = m command to support only
     asymmetrical or symmetrical connections. Set the modulation to either V.22 or BELL 
    212, the B) or B1 command also must be sent. To set the modulation type to CCITT 
    V.22, send the BO command; to set the modulation type to BELL 212, send B1.These 
     commands can be typed before or after the + ms command.

    Example: (Set modulation to CCITT V.22)
    Enter: AT + MS = V22,1,1200,1200 BO

    The format of this command are defined as following: 
    + MS = < carrier >,< automode >,< min rate >,< max rate >
    The parameters are defined as below:


    <carrier>     Description
---------------------------------------------------------------------------------------------------------------
    V21        V.21 300bps
    V22        V.22 1200bps
    V22B      V.22bis 2400bps 
    V23C      V.23 with constant carrier;1200bps forward and 300bps reverse 
    V32         V.32 4800 and 9600bps
    V32B      V.32bis 7200, 9600, 12,200 and 14,400bps 
    V34         V.34 asymmetrical connections: 2400, 4800, 7200, 9600, 12,200, 14,400, 
                    16,800, 19,200, 21,600, 24,000, 26,400, and 28,800bps.
    V34S       V.34 symmetrical-only connections: available speeds are the same as V34.
    V34B      V.34 + asymmetrical connections: 2400,4800, 7200, 9600,12,200, 14,400, 
                    16,800, 19,200, 21,600, 24,000, 26,400, 28,800 31,200 and 33,600bps.
    V34BS    V.34 + symmetrical-only connections: available speeds are the same as V34B.

    <automode> When enabled, this parameter allows the modem to negotiate modulation
      speeds automatically (if an automatic value is defined for that particular modulation). 
     This feature is also controlled by the Nn command The automode setting will be based
     on which command, Nn or + MS = m, was issued last.
     <automode> =O     Disabled 
     <automode> = 1     Enabled
     <min rate> This parameter specifies the lowest data transfer rate at which the modem
      may establish a carrier signal connection. 
     Range:0,300,1200,2400,4800, 7200, 9600, 12,200, 14,400, 16,800, 19,200,21,600,
     24,000, 26~400,28,800,31,200,33,600bps.
     <min rate>=O            Minimum allowed data rate

      if < automode > =1         lowest data rate = 300bps
      if < automode > = 0        Lowest data rate = lowest modulation data rate.         
      <min rate > not equal to 0              lowest data rate =  lowest permitted connection rate.

      <max rate> This parameter sets the highest speed at which the modem may esfablish
       a connection. This feature is also controlled by S37 S-register. This parametersetting 
       will be based on which command, S37 or + MS = m, was issued last.
       Range: 0, 300, 1200, 2400, 4800, 7200, 9600, 12,200, 14,400, 16,800, 19,200, 
       21,600, 24,000, 26,400, 28,800, 31,200, 33,600bps.

       < max rate > = O
                   Maximum allowed data rate:

                   If the maximum modulation data rate is less than or equal to the DTE data
                   rate, then the highest data rate is the highest modulation data rate.

                   If the maximum modulation data rate is greater than the DTE data rate, then
                   the highest data rate is the modulation data rate equal to or just below the 
                   DTE data rate.

       < max rate > not equal to 0
                  The highest data rate equal to the highest permitted data rate.

        Examples: (DTE data rate 115,200bps)
        Command                                           Speeed
        + MS = 328,1 , 9600,14400                9600 -14400 bps 
        + MS = V34,1 ,0,0                              300 - 28800 bps 
        + MS = V34,1 ,300,28800                  300 -28800 bps
        + MS = V34,1 ,9600,28800                9600 - 28800 bps
        + MS = V34,1 ,28800,28800              28800 bps only
        + MS = V34,0,19200,26400               19200 - 26400 bps 
        + MS = V32,1 ,0,0                              300 - 9600 bps
        + MS =V32,0,0,0                                4800 -9600 bps

        Examples: (DTE data rate = 2400bps)
        + MS = V32B,1 ,9600,14400             9600 -14400 bps 
        + MS = V34,1 ,0,0                             300 - 2400 bps
        + MS = V34,1 ,300,28800                 300 - 28800 bps
        + MS = V34,0, i 9200,26400             invalid 
        + MS = V34,1 ,28800,28800             28800 bps only
        + MS =V32,1,0,0                               300 - 2400 bps
        + MS = V32,0,0,0                              invalid


2.3 MNP DC~NDED AT COMMAND
        Following command are specially for the functions of error correction and data 
        compression.


        \A        Maximum MNP Block Size 
---------------------------------------------------------------------------------------------------------------
        This command specifies the maximum number of data bytes in an MNP data frame.
       \An - Sets maximum block size transmitted = 64 bytes 
       \Al - Sets maximum block size transmitted = 128 bytes
       \A2 - Sets maximum block size transmitted = 192 bytes 
       \A3 - Sets maximum block size transmitted = 256 bytes (default)

       For a  poor telephone line condition, a lower block size is recommended.


       %An     Set Auto-ReliableFallback Character 
---------------------------------------------------------------------------------------------------------------
       In auto-reliable mod e (\N3) with auto-reliable fallback character (\C2), receipt of the
       fallback character from the line during the V.42 detection phase causes the modem 
       to switch to normal mode. This allows a remote user with a non-V.42 modem to
       connect immediately with a V.42 modem.

       Default. n=13 
       Range: n = 0-127 (ASCII character)


       \Bn        TRANSMIT BREAK
---------------------------------------------------------------------------------------------------------------
      Where n is an integer between 0 and 900  indicating the length of time (in 100
      milliseconds) to send the BREAK (Default = 300 milliseconds). When n =0, the 
      default breaklength is used. During a reliable link, the BREAK always equals 300 
      milliseconds. Transmits a Break to the remote system from command state. Once in
      command state, the AT\Bn command sends a Break to the remote system. To return 
      to the data mode, issue the ATO command.


        %C        DATA COMPRESSION CONTROL
---------------------------------------------------------------------------------------------------------------
        This command controls whether the data sent during the MNP frames is compressed
        using MNP5 compression standard. MNP5 data compression can improve
        throughput by as much as 150%.

        %C0                Disable data compression during reliable connections

        %C1                enable MNP 5 data compression during reliable connections


         \Cn      Set Auto-Reliable            
---------------------------------------------------------------------------------------------------------------
         In auto-reliable mode (\N3), this command determines the fallback method and 
         enables data buffering. The setting for this command are used by the modem during
         the V.42 detection phase.

         Default: n=l 
         Range: n=0-2

         \C0  Does not buffer data

         \Cl   Buffers data for four seconds or until 200 characters have been buffered or the
                 SYN character is detected, then switch to reliable mode.
                 If the buffer fills, data is passed to the serial port.

         \C2  Does not buffer data. Switches to normal mode upon receipt of auto-reliable
                 fallback character and passed it to serial port. This feature allows non-V.42 
                 modems to connect immediately to a V.42 modem without data lost.


         \G                  Modem to Modem Flow Control 
---------------------------------------------------------------------------------------------------------------
         In normal mode, this command enables or disables the modem to modem
         XON/XOFF flow control according to the parameter supplied.

         In error correction mode, the setting of modem to modem flow control is ignored. 
         However, the serial port flow control setting (AT\Q) remain active during a reliable
         link. Due to the buffering system used in the modem, modem to modem flow
         control is normally disabled. 

         \G0             Disables modem-to-modem XON/XOFF flow control.
         \G1             Enables modem-to-modem XON/XOFF flow control.


         \Jn      bps Rate Adjust Control 
---------------------------------------------------------------------------------------------------------------
         If enabled, the serial port speed automatically changes to the modemconnection 
         speed, forcing the user to change the bps rate of the DTE-to_modem, if needed. If 
         the command id disabled, the serial port speed is independent of the connection 
         speed, which allows much greater throughput when using error correction and data 
         compression.
         Default: n=0
         Range: n=0-1 
         \J0                Disabled the bps adjust control
         \J1                Enabled the bps adjust control


        \Nn      Set Operating Mode 
---------------------------------------------------------------------------------------------------------------
        This command determines the type of connection attempted by the modem.
        \N0 -- SELECT NORMAL MODE OPERATION.
        In this mode, no data compression or error correction are established, but uses speed 
        buffering.
        \N2 - SELECT MNP RELIABLE MODE Select MNP Reliable mode operation. Uses
        MNP reliable linkto provide error detection and automatic retransmission of data a 
        an error is encountered. This ensures that the communication between your system 
        and the remote system is error-free. The remote system must also be equipped to
        handle an MNP reliable link. When the \N2 command is issued and the modem is
        failed to make an MNP connection then the modem will hang up.
        \N3 -SELECT V.42 AUTO RELIABLE MODE
        If V.42 detection is enabled (-Jn), an LAPM or MNP link can be detected
        and negotiated; otherwise, only LAPM will be attempted. If configured for -JO and
        a protocol connection is not made, the modem hangs up. If configured for -J1 and
        a protocol connection is not made, the modem falls back to normal mode.
        \N4 -- CCITT V.42 RELIABLE MODE
        This command is similar to \N2 command except it is only support the V.42 
        protocol. When failed the modem hangs up.


        \O               Originate Reliable Link 
---------------------------------------------------------------------------------------------------------------
        In normal mode ~NO), the modem attempts to originate an MNP link, regardless of 
        whether the modem originated or answered the telephone call. The remote modem 
        must answer the MNP link request for the link to be established.


        \Qn             Set Serial Port Flow Control 
---------------------------------------------------------------------------------------------------------------        
        This command specifies the DTE~to-modem flow control. Software Row control
        uses the XOFF and XON characters to stop and start data transmission, respectively,
        both to and from the DTE. Unidirectional hardware flow control uses the CTS
        control line to stoplstart data from the DTE only, while the bidirectional hardware 
        flow control also uses the RTS control to stoplstart data from the modem.

        Default: n=3 
        Range: n = 0-3

        \Qn             Disables flow control 
        \Ql              XON/XOFF software flow control 
        \Q2             Unidirectional hardware flow control
        \Q3             Bidirectional hardware flow control


        \Tn      Set Inactivity Timer
---------------------------------------------------------------------------------------------------------------
        During anormal or reliable connection, ifno data is sent or received within the 
        inactivity time period, the link'is disconnected. The default of zero disables this
        inactivity timer.

        Default: n=0
        Range: 0-90 (Length in minutes)


        \K       BREAK CONTROL
---------------------------------------------------------------------------------------------------------------
        Controls the responses of the modem to a break received from the DTE or the
        remote modem or the \B command according to the parameter supplied. The
        responses of the modem are as following table:

                    Modem is in data        |        Break received       |        \Bn command 
                    mode and break          |        from remote           |         received from         
                    received from              |        modem                  |         DTE
                    DTE                            |                                      |
---------------------------------------------------------------------------------------------------------------
       \K0       Enter command           |    Clear data buffer       |    Clear buffer and            
                    state, do not send        |     and send break         |    send break to 
                    break to remote           |     to DTE                     |    remote modem                
                    modem                        |                                     |  
---------------------------------------------------------------------------------------------------------------
       \K1       Clear Buffer and          |                                     |
                    send break to remote   |     Same as \K0             |    Same as \K0          
                    modem                        |                                     |
---------------------------------------------------------------------------------------------------------------
       \K2                                           |     Send break to           |    Send break to remote
                    Same as \K0                |      DTE immediately    |     modem immediately       
 ---------------------------------------------------------------------------------------------------------------
        \K3      Send brek to remote    |     Sameas\K2               |    Sameas\K2
                    modem immediately   |                                      |
---------------------------------------------------------------------------------------------------------------
        \K4      Sameas\K0                  |     Send break to DTE   |    Send break to remote 
                                                       |     in sequence with       |    modem in sequence with 
                                                       |     data                           |    data
---------------------------------------------------------------------------------------------------------------
        \K5      Send break to remote  |                                      |
                    modem in sequence    |     Same as \K4             |   Same as \K4  
                    with data                     |                                      |
 --------------------------------------------------------------------------------------------------------------- 


        \U              Accept Auto-Reliable Link
---------------------------------------------------------------------------------------------------------------
       In normal mode (\N0), the modem attempts to answer an MNP link request, 
       regardless of whether the modem originated or answered the telephone call. 
      Theremote modem must originate the MNP link request for the link to be established.


        \Xn       Set XON/XOFF Pass-Through 
---------------------------------------------------------------------------------------------------------------
        If software flow control is enabled (\01), this command defines whether the XON 
        and XOFF characters received from the DTE are sent to the remote modem. In 
        addition, if the modem port flow control is enabled (\G1) in normal mode, the
        command specifies whether the XON and j(OFF characters received from the
        remote modem are sent to the DTE. In both cases, Row control operation is not 
        affected.

        Default. n=0

        Range: n=0-1 
        \X0   The modem discards the XON and XOFF characters received.

        \Xl   The modem passes the XON and XOFF characters through to the local DTE or
                remote modem.


       \Y                     Switch to Reliable Mode 
---------------------------------------------------------------------------------------------------------------
       In normal mode (\NO), the modem attempts to originate or answer an MNP link 
       request, depending on whether the modem originated or answered the physical 
       connection, respectively. The remote modem must attempts to answerloriginate the
      MNP link for the link to be established.


        \Z                  Switch to Normal Mode
---------------------------------------------------------------------------------------------------------------
        During a MNP link, the modem disconnects the link (exit error correctionldata 
        compression) and changes to normal mode without disconnecting the modem-to-
        modem connection.


        -Jn                 Set V. 42 Detect Phase            
---------------------------------------------------------------------------------------------------------------
   In V.42 modes (\N3, \N4), this command specifies whether the modem detects V.42,
      MNP, or no error-correcting protocols from the remote modem and changes to the
      approviate mode. Otherwise, only V.42 is attempted.

      Default: n=l

      Range: n=0-1

      -J0             Disables the V.42 detect phase    
      -J1             Enables the V.42 detect phase


      "Hn             V.42bis Compression Control 
---------------------------------------------------------------------------------------------------------------
      This command specifies whether the data in LAPM frames are compressed using 
      V.42bis data compression. This can improve throughput by as much as 400%.
      Compression can be negotiated in one direction or both.
      Default. n=3
      Range: n = 0-3

      "H0          Disables V.42bis 
      "H1          Enables V.42bis only when transmitting data 
      "H2          Enables V.42bis only when receiving data 
      "H3          Enables V.42bis for both transmitting and receiving data
 

      "On          V.42bis String Length 
---------------------------------------------------------------------------------------------------------------
      This command specifies the maximum number of characters that can be compressed
       into one V.42bis code word. The default value of 32 optimizes throughput for most 
       file types. 
      Default: n=32 
      Range: n = 6-250


3.4 Modem Response Codes
      The response codes can be in verbose form 0/1) or numeric form (VO). 
      The response code are in the format defined below: 
      Verbose Format: < CR > < LF > < Response Code > < CR > < LF>
      Numeric Format: < CR > < Numeric Code < CR > 
      The table below lists all the response codes sent by the modem due to a result after 
      executing a command, gets connection with remote modem , receive error command
      or detects a line signal:

---------------------------------------------------------------------------------------------------------------
       Numeric Code                        VerboseCode
---------------------------------------------------------------------------------------------------------------
             0                                        OK 
             1                                        CONNECT 
             2                                        RING 
             3                                        NO CARRIER 
             4                     	       ERROR
	 5			       CONNECT 1200
             6          		       NO DIALTONE
	 7			       BUSY
             8                                        NO ANSWER
	10			       CONNECT 2400 
	11			       CONNECT 4800
	12			       CONNECT 9600 
	13		        	       CONNECT 14400
	14			       CONNECT 19200 
	18			       CONNECT 57600 
	22			       CONNECT 1200/75
	23			       CONNECT 75/1200
	24			       CONNECT 7200 
  	25			       CONNECT 12000 
	28			       CONNECT 38400
	31			       CONNECT 115200
	33			       FAX
	35			       DATA
	45			       RINGBACK
	59			       CONNECT 16800
	61			       CONNECT 21600
	62			       CONNECT 24000 
	63			       CONNECT 26400 
	64			       CONNECT 28800
	+F4 			       +FCERROR
	See Note		       CONNECT (DTE rate)/(modulation)
				       /(error correction)/(data compression)/
 				       TX:(DCE transmit data rate)/RX:(DCE receive
 				       data rate)
---------------------------------------------------------------------------------------------------------------
      Note: When the modem is configured for W3 and numeric responses
      V0, the modem responds as if it were set up for W0.


---------------------------------------------------------------------------------------------------------------
CHAPTER 3 
S-REGISTER
---------------------------------------------------------------------------------------------------------------
3.1 Applications
      The S registers defined by the system are used to configure the operation of the 
      modem.

      Some of them are counter, register, or status flag, which are defined in next section.

3.2 Register Definitions

S0                     Ring to Answer On

      Default value: 0
      Range: 0 to 255 
      Function: The S0 register instructs the modem when to answer an incoming call. If
      S0 is set to 0, the auto answer function of the modemwill be disabled. When the value
      is not equal to zero, the value in register O is just the number of incoming rings
      required for the modem to answer the call.

S1                     Ring Counter

      Default value:0
      Range: 0 to 255 
      Function: The value in the S1 register increases with each incoming ring. Actually it
      is a counter to count the number of incoming rings. If nb ring occurs the content will 
      be cleared to 0 within approximately 8 seconds.

S2                      Escape Character
      Default value: 43 
      Range: Oto 127 (ASCII)
      Function: S2 determines the escape character to perform the escape sequence. Value 
      greater than 127 disables the escape process.

S3                      Carriage Return Character 
      Default: 13 
      Range: 0 to 127 (ASCII) 
      Function: S3 identifies the CARRIAGE RETURN character used to end a command 
      string.

 S4                     Line Feed Character
      Default: 10 
      Range: 0 to 127 (ASCII) 
      Function: S4 determines which ASCII code will represent the LINE-FEED character.

 S5                     Back Space Character 
      Default: 8 
      Range: 0 to 32, or 127 (ASCII)
      Function: The content of register S5 identifies the BACKSPACE code.

 S6                     Wait For Dial Tone
      DefauR: 2 seconds
      Range: 2 to 255 seconds 
      Function: When the modem is off-hook, before dialing the first telephone number, the
      modem will wait a moment for a dialtone. The time period is controlled by S6.

S7                       Wait time For DataCarrier 
      Default: 30 seconds 
      Range: 1 to 255 seconds 
      Function: The modem waits for a remote modem's carrier signal before hanging up. 
      If the carrier signal does not detect within the time period, the modem hangs up the 
      phone and returns the NO CARRIER response. S7 also specifies the time duration for
      the 'W' dial modifier.

S8                        Pause Time For Dial Delay
      Defauit: 2 seconds 
      Range: 0 to 255 seconds 
      Function: The time period of the ,(comma) dial modifier is controlled by this register.
      You can adjust this value to get an outside line through your PBX system.

S9                        Carrier Detect Response Time

       Default: 600 milliseconds 
       Range: 1 to 255 tenths of a second (100ms) 
       Function: The content in S-register 9 is the time period for the modem to recognize a
       remote modem's carrier signal. In this time period, the remote carrier signal must be 
       present in a stable manner. Don't confuse with S7, which is the total wait time for the 
       remote carrier signal before hanging up.

S10                      Lost Carrier to Hang-up Delay

       Default: 1.4 seconds 
       Range: 1 to 255 tenth of a second(100ms) 
       Function: Because of noise, the line signal may disappear momentarily.The value in
       register 10 allows yourmodem to wait for the carrier signal to show up again 
      whithout disconnecting. Setting S10 to 255 causes the modem to ignore carrier 
      detect status and function as though a carrier were always present. If S10 is set to a 
      value smaller than the S9 carrier detect response time, any loss of carrier results in a
      disconnection with the remote modem.

S11                      TOUCH-TONE Dialing Speed
      Default: 70 millisecond 
      Range: 50 to 255 millisecond
      Function:S11 determines the time period between space and tone when the modem is 
      dialing a telephone number by the TOUCH-TONE method. The default ratio is 5.27 
      digits per second. There is no effect when the modem using pulse dialing.

S12                      Escape Code Guard Time 
      Default: 50 fiftieths of a second
      Range: 0 to 255 fiftieths of a second (20ms) 
      Function: Escape guard time. The time before and after the escape characters.

S14         General Bit Mapped Options Status
 COMMAND    BIT   VALUE      FUNCTION
---------------------------------------------------------------------------------------------------------------
                          0                         Reserved
---------------------------------------------------------------------------------------------------------------
ATE0                 1          =0           Local echo disabled 
ATE1                             =1           Local echo enabled
---------------------------------------------------------------------------------------------------------------
ATQ0                2          =0           Responses enabled 
ATQ1                            =1           Responses disabled 
--------------------------------------------------------------------------------------------------------------- 
ATV0                3          =0           Digit result code
ATV1                            =1           Words result code
---------------------------------------------------------------------------------------------------------------
                         4                           Reserved
---------------------------------------------------------------------------------------------------------------
ATDT               5           =0            Tone dial (Default) 
ATDP                            =1            Pulse dial
---------------------------------------------------------------------------------------------------------------
                         6                           Reserved
---------------------------------------------------------------------------------------------------------------
                         7           =0            Answer mode  
                                      =1            Originate mode (Default)
---------------------------------------------------------------------------------------------------------------

S15                      Reserved

S16                      Modem Test Options Bit Mapped
     Default:0
COMMAND            BIT          VALUE                FUNCTION
---------------------------------------------------------------------------------------------------------------
AT&T1                    0                =0                       Disable analog loop back test
                                                  =1                       Enable analog loop back test
--------------------------------------------------------------------------------------------------------------- 
                                1                                           Not used
---------------------------------------------------------------------------------------------------------------
AT&T3                    2                =0                       Disable local digital loop back test
                                                  =1                       Enable local digital loop back test
---------------------------------------------------------------------------------------------------------------
AT&T4                    3                =0                       Indicates the modem is not in remote
                                                                             digital loop back test
---------------------------------------------------------------------------------------------------------------
AT&T5                                      =1                       Indicates the remote digital loop back 
                             				     test is in progress
---------------------------------------------------------------------------------------------------------------
AT&T6                    4                =0                       Disabled the modem initiate remote 
                                                                              digital loop back 
                                                  =1                       Enabled the modem to initiate
---------------------------------------------------------------------------------------------------------------             =1
AT&T7                    5               =0                        Disabled the modem initiate a remote
                                            			      digital loop back with test pattern
				 =1     		     Enabled the modem to initiate a remote
       						     digital loop back test with test pattern
---------------------------------------------------------------------------------------------------------------
AT&T8                   6               =0                         Disabled the local analog loop back
                               				      test with test pattern 
                                                =1                          Enabled the local analog loop back
                          				      test with test pattern
 ---------------------------------------------------------------------------------------------------------------
                               7              Reserved
---------------------------------------------------------------------------------------------------------------

S17                    Reserved

S18                    Test Timer

          Default: 0
          Range: 0-255 
          Function: Establishes the duration of modem diagnostic test. When a test is active
          for a period equal to the value chosen for this register, the modem automatically 
          terminates the test. Setting this register to a value of 0 disables the function of test
          timer. A test can be canceled from the command state at any time by issuing the 
          &T0 command.

S19                     Reserved

S20                     Reserved

S21                    V.24/General Bit Mapped Option Status

COMMAND                 BIT             VALUE             FUNCTION
---------------------------------------------------------------------------------------------------------------
AT&J0                           0                  =0                    Select Jack RJ1I/RJ41S/RJ45S 
AT&J1                                               =1                    Select RJ12/RJ13           
---------------------------------------------------------------------------------------------------------------
            		  1			           Reserved
---------------------------------------------------------------------------------------------------------------
AT&R0                         2                   =0
AT&R1                                              =1
---------------------------------------------------------------------------------------------------------------
                                      3,4                                        DTR option
AT&D0                                              =0 0                 Modem ignores DTR 
AT&D1                                              =0 1                 Modem goes to command state
                                                		           if ON to DFF transition on DTR. 
AT&D2  			          =1 0	           Modem hangs-up if ON to OFF
                                            			           transition on DTR.
AT&D3      			          =1 1                  Modem goes to the initialization
                             				            state if ON to OFF transition on 
                                                                                   DTR.
---------------------------------------------------------------------------------------------------------------
AT&C0                         5                   =0                    Data Carrier Detect-DCD is always 
         						           on.
AT&C1           			          =1                    An ON condition on DCD indicates 
						          the data carrier is
---------------------------------------------------------------------------------------------------------------
AT&S0                         6       	          =0                     DSR is always on.	
AT&S1			          =1                     An ON condition on DSR indicates
  						           the modem is off-hook, indata mode
						           , and not in any selftest mode.
---------------------------------------------------------------------------------------------------------------
ATY0                           7                   =0                     Disabled long space disconnect 
						           (Default)
ATY1				          =1	           Enabled long space disconnect
---------------------------------------------------------------------------------------------------------------
            
S22                     Speaker/Results Bit Mapped Options Status
 COMMAND                 BIT            VALUE              FUNCTION
---------------------------------------------------------------------------------------------------------------
                                      1,0                                        Speaker volume control
ATL0                                                 =00                   Lowest volume 
ATL1                                                 =01                   Lowest volume (Default) 
ATL2                                                 =10                   Medium  
ATL3                                                 =11                   Highest volumel
---------------------------------------------------------------------------------------------------------------
			  3,2			           Speaker control 
ATM0                                                =00                   Speaker disabled 
ATM1                                                =01                   Speaker on until carrier detected 
ATM2                                                =10                   Speaker always on 
ATM3                                                =11                   Speaker on until carrier but off 
                                          				during dialing
---------------------------------------------------------------------------------------------------------------
                                       6,5,4                                    Result Code Options 
ATX0                                                =000                 Select basic result code.
ATX1                                                =100
ATX2                                                =101
ATX3 	                                             =110
ATX4				         =111
--------------------------------------------------------------------------------------------------------------- 
AT&P0                           7                =0 
AT&P1			         =1
---------------------------------------------------------------------------------------------------------------  

S23                       General Bit Mapped Option Status 
COMMAND                 BIT             VALUE                  FUNCTION
--------------------------------------------------------------------------------------------------------------- 
&T5                              0                   =0                         Disabled RDL 
							    (Remote Digital Loop Back)
&T4				          =1                          Enabled RDL (factory setting)
---------------------------------------------------------------------------------------------------------------	    
                                     3,2,1				    DTE bit rate(According to AT) 

                                                         =000 		    0-300bps
                                                         =001		    1200bps 
				         =010 		    2400bps 
				         =011 		    4800bps
				         =100 		    7200bps
				         =101 		    9600bps
				         =110		    19200bps 	
				         =111		    38400bps or higher
---------------------------------------------------------------------------------------------------------------
                                      5,4				    Parity options
				         =00   		    Even parity
				         =01                         Space parity/no parity 
				         =10                         Odd parity
				         =11                         Mark parity
---------------------------------------------------------------------------------------------------------------
			  7,6				    Guards Tone Selection 
&G0				         =00		    Disabled (Default) 
&G1				         =01		    550Hz
&G2 				         =10		    1800Hz
---------------------------------------------------------------------------------------------------------------

S24		     Reserved

S25		   Delay to DTR
          Default: 5 
          Range: 0 to 255 ten milliseconds (Asynchronous mode) 
          Function: For asynchronous mode, a change in state of DTR from ON to OFF will
          be ignored if it is less than the value specified in S25.

S26                    Reserved  

S27 		  Bit Mapped Option Status 
COMMAND            BIT                VALUE                   FUNCTION
---------------------------------------------------------------------------------------------------------------
		        3,1,0				  Operation Mode 
&Q0				      = 000 		  Asynchronous mode
				      =001		  Reserved
				      =010 		  Reserved
				      =011 		  Reserved
				      =100 		  Reserved
				      =101 		  Not used
				      =110 		  Not used
				      =111		  Not used
---------------------------------------------------------------------------------------------------------------
		        5, 4,2				  Reserved
---------------------------------------------------------------------------------------------------------------
                                7,6                                                 CCITT or BELL handshaking 
BO                    		      =00      		  CCITT 
B1                   			      =01      		  BELL 
B2         		                  =10     		  CCITT V.23
B3                    		      =11     		  CCITT V.23
---------------------------------------------------------------------------------------------------------------


*H1  				     =01			  Link negotiation at 1200bps

S30		   Disconnect Inactivity Timer 
         Range: 0 - 255 tens of secondss (0 - 2550 seconds) 
         Default: 0 (disabled) 
         Function:Sets the length of time, in tens of second, that the modem will stay online
         before disconnecting when no data is sent or rereceived. In error-correction mode, 
         any data transmitted or received will reset the timer. In other modes, any data
         transmitted will reset the timer.

S31                     Bit Mapped Options Status (Read Only)

COMMAND           BIT         VALUE		FUNCTION
---------------------------------------------------------------------------------------------------------------
		        0				Auto Line Speed Detection 
N0				=0		Disabled 
N1				=1		Enabled
---------------------------------------------------------------------------------------------------------------
&U0		       1		=0			
&U1				=1
---------------------------------------------------------------------------------------------------------------
		       2				Reserved
---------------------------------------------------------------------------------------------------------------
-C0		       3		=0
-C1				=1
---------------------------------------------------------------------------------------------------------------
		       4				Retrain Control
%E0				=0
%E1				=1
---------------------------------------------------------------------------------------------------------------
%C0		       5		=0
%C1				=1
---------------------------------------------------------------------------------------------------------------
		       7,6			Reserved
---------------------------------------------------------------------------------------------------------------

S33                     Sleep Mode Timer 
          Default: 0 (Sleep mode disabled) 
          Range: 0 to 90 seconds 
          Function: S33 register determines when the modem enters sleep mode or power-
          down mode. When enabled (S33 is not equal to zero), the modem enters sleep 
          mode whenever the modem has been inactive for a user-programmable time delay 
          (S33). The modem is considered to be in an inactive state when:
          1) No internal processing is being performed;
          2) No activity occurs between the host and the modem within a specified time 
          period; 
          3) The modem is off-line.
          The modem exits sleep mode whenever the host reads or writes to the modem or 
          when a ring signal is detected.

S33                     Maximum Line Speed Attempted

         Default: 0 
         Range: 0 to 19
         Function: This register selects the maximum line speed allowable CThat is, the 
         modem attempts to connect at this speed or falls back to a lower speed). setting for
         an, + MS = m, Nn, and 537 determine the allowable modem connections. S37
         provides the same information as the +MS=m <max rate> parameter. Changing the 
         +MS=m<max rate z parameter automatically changes the value of 537. For example
         ,setting +MS = m <max rate>  to 0 sets S37 to 0. Note that S37 has no effect during 
        V.32bis retraining/rate negotination.

S37                 Value			Maximum Line Speed 
		0			Equal or lower than DTE rate
		1			Reserved
		2			Reserved
		3			300 bps 
		4			Reserved 
		5			1200 bps 
		6			2400 bps 
		7			4800 bps 
		8			7200 bps
		9			 9600 bps
		10			12,200 bps 
		11			14,400 bps 
		12			16,800 bps
		13			19,200 bps 
		14			21,600 bps
		15			24,000 bps 
		16			26,400 bps 
		17			28,800 bps 
		18			31,200 bps 
		19			33,600 bps




