SPORTSTER 14,400
                                CHAPTER 6.  DIALING AND ANSWERING
                                                                 
      
BEFORE CONNECTING

      For two modems to connect and exchange
      data, they must use the same modulation
      standard and, for error control to be
      successful, the same error-control
      protocol.
      
Modulation/Standards

      The Sportster 14,400 modem conforms to
      the following modulation and signaling
      standards.
       CCITT V.32 bis 14.4K/12K/9600/7200/4800
                 bps
       CCITT V.32     9600/4800 bps
       CCITT V.22 bis  2400 bps
       Bell 212A/
       CCITT V.22 1200 bps
       CCITT V.23     1200 bps with 75-bps
                 back channel (sometimes used
                 in U.K. and Europe)
       CCITT V.25     Answer sequence for
                 calls originating outside the
                 U.S. and Canada
       Bell 103/
       CCITT V.21 300 bps
       CCITT V.42     LAPM error control, 1200
                 bps and above
       CCITT V.42 bis Data compression, 1200
                 bps and above
       MNP      Levels 2, 3 and 4 error
                 control, level 5 data
                 compression, 1200 bps and
                 above
       CCITT V.54     Analog, digital and
                 remote digital loopback
                 testing
                 
Setting the Transmission Rate

      Setting your software to 38.4K or 19.2K
      bps ensures that the Sportster 14,400
      can operate at its highest rate.  The
      modem detects the rate from the AT
      command, operates at that rate at the
      serial port, and tries to connect with
      remote modems at 14.4K bps, its highest
      connection rate.
      Follow the guidelines in Chapter 3,
      Quick Start, or the more detailed
      instructions in Chapter 4 before
      selecting either variable or fixed
      serial port rates (&Bn).  If your
      software supports a fixed serial port
      rate, set the modem to &B1 and your soft
      ware to a high serial port rate for the
      best throughput.  Set the modem for flow
      control (&Hn), as well.
      We recommend leaving the modem at its
      link operation factory setting, &N0,
      unless your application requires that
      you specify a fixed connection rate.
      &N0 allows the Sportster 14,400 to auto
      matically negotiate with the remote
      modem for the highest possible
      connection rate.
      
Data Format

      Both your machine and the remote
      computer must use the same 10-bit data
      format, which always consists of 1 Start
      bit, plus one of the 9-bit combinations
      listed in Table 6.1.  You may have to
      phone the remote computer installation
      or BBS to find out what word length,
      parity and Stop bit combination is
      required.
      Before calling, set your communications
      software (or terminal if you are using
      one) to the required scheme.  Some commu
      nications programs use a kind of
      shorthand for formats, such as 7-E-1 or
      8-N-1.  The modem detects the format
      from the AT prefix of the next command
      it receives from your keyboard or from
      your software.
            Table 6.1_Allowable Data Formats
                       
              Word    Parity     Stop
             Length  (1 Bit)     Bits
               7    Even, Odd,    1
                   Mark, Space
               7       None       2
               8       None       1
           
Error Control

      For reliable high-speed data transfer,
      always set the Sportster for error
      control, &M4 (default) or &M5, for calls
      at speeds over 2400 bps.  Most users
      communicating with V.42- or MNP-
      compatible modems will want error
      control at 2400 and 1200 bps, as well.
      The &M command is described in Chapter
      4.
      If you're dialing out, it's a good idea
      to find out if the remote modem is MNP-
      compatible.  Some public network
      services, for example, are not.  If the
      remote modem doesn't have MNP capa
      bility, it may misinterpret the MNP
      error-control request and block a
      successful connection.  If you know the
      remote modem doesn't support MNP, dis
      able MNP handshaking by setting Register
      S27 to 16 (ATS27=16).  The modem still
      connects with V.42-compatible modems and
      modems that do not perform error
      control.
      To reset the modem for normal opera
      tions, issue the ATZ (reset) command,
      or set Register S27 to zero.
      
PLACING CALLS

      This section discusses commands used in
      the following operations.
         Dialing    D (0-9 # * , / ; " ! P T
           W @ R), DS
         Redialing  A/
         Canceling dialing<any key>
           
Dial (D)

      The following command example instructs
      the modem to stop the display of
      commands (E0, turn off the local echo),
      turn off the speaker (M0), and dial (D)
      the phone number (1234567) using Touch-
      Tone dialing (T).  The spaces shown are
      ignored by the modem and are only
      included here for readability.
             AT E0 M0 DT 1234567 <Enter>
      When the Dial command is issued, the
      modem goes off hook_ the equivalent of
      picking up your phone_then enters
      Originate mode and dials the number
      sequence that follows.  The modem also
      executes any other commands or options
      included in the command line.
      The dial string may include up to 40
      characters.  The modem counts but
      ignores punctuation characters such as
      parentheses and hyphens.  It does not
      count spaces, the AT prefix or the
      carriage return (Enter key) required to
      execute the command.
   Cancel Dialing
      To cancel Dial-command execution, press
      <any key>.  If you inadvertently hit a
      key on the keyboard while the modem is
      dialing, the call is canceled.  If this
      occurs, type the A/ command (explained
      under Redialing later in this chapter).
      On receipt of A/, the modem redials.
      
Dial Command Options

      You may want to review the many options
      on the next several pages that are
      available for tailoring Dial strings.
      The most typically used are the Dial
      Type, Pulse or Tone, and the Pause
      options_comma, slash and W.
   Dialing Type, Pulse or Tone
      The modem is shipped to default to pulse
      (rotary) dialing.  To have the modem use
      tone dialing, which includes the
      asterisk (*) and pound sign (#), use the
      T command.
      Dialing type commands may be included in
      the Dial string (ATDT number), issued
      separately (ATT or ATP), or included in
      the &W default configuration string you
      write to NVRAM, as explained in Chapter
      5.  You can also set the X2, X3 or X4
      result code options, which include
      adaptive dialing, explained next.
      NOTE:  You can switch from one dial type
      to another within a dialing sequence.
      Keep in mind that the modem remains set
      to the last dialing type instruction
      until it is reset (ATZ command) or it
      receives a different dial-type command.
   Adaptive Dialing (X2OX4)
      When any of the X2 through X4 options is
      in effect and you do not issue a dialing
      type in the Dial string, the Sportster
      14,400 uses tone dialing, which is
      faster than the default pulse type.  How
      ever, if the phone company's central
      office does not have Touch-Tone
      detection equipment, the modem cannot
      break dial and continues to detect the
      dial tone.  If this occurs, the modem
      automatically reverts to pulse dialing.
   Pause (,)
      A comma causes a two-second delay in the
      dial sequence.  The following example
      contains four-second delays at several
      points.
             ATDP 9,,7654321,,55555,,1 312
             1234567 <Enter>
      The first four-second pause is to access
      an outside line after dialing 9, but you
      may wish to use the W option, described
      below.  The second pause is to make sure
      the remote system is ready for the
      user's account number, and the third, to
      delay before dialing the long-distance
      number.
      Such pauses, however, may not be
      necessary.  Experiment and use delays
      only as required.
   Slash (/)
      A slash (/) can be used in any command
      string to make the modem pause for only
      125 milliseconds.  Some users find it
      helpful to have the shorter delay of a
      series of slashes, rather than the 2-
      second comma pause.
   Wait for Another Dial Tone (W)
      This command is useful in situations
      where you must wait for a second dial
      tone before continuing dialing.  For
      example, if you need to dial for an
      outside line, as in the following exam
      ple, the Sportster 14,400 continues
      dialing as soon as it detects the next
      dial tone.
             ATD9W1234567 <Enter>
      NOTE:  This command executes only if
      result code option X3 or greater has
      been issued.  If the modem is set to X2
      or lower, the modem interprets the W as
      a comma (two-second pause).
   Dial and Return to Command Mode (;)
      If your phone is plugged into the modem,
      you can use this option to have the
      modem Auto Dial a telephone rather than
      a modem.  The Sportster 14,400 dials,
      remains off hook and returns the OK
      message, indicating it is in Command
      mode.
      For example, to have the modem place a
      voice call, enter the Dial command with
      a semicolon.
             ATDT5551234; <Enter>
      When the modem returns the OK result,
      pick up your phone receiver so you can
      talk to the other party, and send the
      command that hangs up the modem.
             ATH <Enter>
      Similarly, you can call a recorded
      weather or other service.  Have the
      modem Dial, listen to the recording over
      the modem's speaker and, when you are
      finished, instruct the modem to hang up.
   Dialing Letters (I)
      Quotation marks are used to make the
      modem dial abbreviations and acronyms
      used as phone numbers, such as DIAL USR
      (the USRobotics Sales Department's 800
      number).  The option is called Quote
      mode.  Quotation marks are inserted at
      the beginning of the alphabetic string.
             ATDTIBBS NEWS <Enter>
      NOTE:  If you are including another
      command after the dial string, use
      closing quotation marks before the
      additional command.
   Transferring Calls (!)
      This command applies to modems in
      installations where other modems share
      the phone line.  The modem flashes the
      switch-hook, that is, it goes off hook
      0.5 seconds, on hook for 0.5 seconds,
      and off hook again to dial the specified
      extension.  The following example
      includes instructions to return to Com
      mand mode (;) and to hang up (H).
             ATDT !1234;H <Enter>
   Wait for an Answer (@)
      Some online services answer the phone
      and return a tape-recorded request for
      information before processing trans
      actions.  In such instances, the @
      command can be used in the Dial string
      to tell the modem to detect at least one
      ring, wait for five seconds of silence
      at the other end of the call, and then
      continue to execute the Dial string.
      To use the @ command, set the modem to
      X3 or X4.  If the modem is set to X2 or
      lower, the modem returns an ERROR mes
      sage when encountering the @ character
      in a command string.
      In the next example, the modem is set to
      the X4 result code option and dials a
      banking service.  Each occurrence of @
      in the example indicates a five-second
      wait for silence, that is, for taped
      requests from the bank for a password
      (12345), an account number (6789) and a
      transaction code (2).  The transaction
      code might indicate, for example, a
      request for an account balance.
             ATX4 DT5551234 @ 12345 @ 6789 @ 2
             <Enter>
      If the necessary conditions do not
      occur_no rings, or no following five
      seconds of silence_the modem times out
      as it normally would (after 60 seconds).
      It then sends the message NO ANSWER to
      the screen and aborts the command.
   Reversing Originate/Answer Frequencies (R)
      This command allows calls to an
      originate-only modem.  It reverses the
      modem's originate/answer frequencies,
      forcing the Sportster 14,400 to dial out
      at the answer frequency.  The command
      follows the Dial command, before or
      after the phone number.
             AT D1234567R <Enter>
             AT DR1234567 <Enter>
             
Dialing the Stored Number (DS)

      Chapter 5 includes instructions for
      storing a frequently-used telephone num
      ber in nonvolatile random access memory
      (NVRAM).  To have the modem dial a
      stored number, use the DS command.
             ATDS <Enter>
             
Redialing (A/)

      The most frequent reason for redialing
      is receipt of a busy signal.  Use the A/
      command, which does not take the AT
      prefix or a Carriage Return, to redial.
             A/
      When the modem receives a command, it
      stores it in its command buffer until
      it receives the next AT command.  Note
      that if you've sent the modem an
      additional command since the Dial
      command, A/ repeats that command
      instead of redialing.
      
ESCAPE CODE OPERATIONS (+++)

      Once the modem is online to another
      system, the only command it recognizes
      is an escape code of three pluses, which
      forces the modem into online-command
      mode.  Issue the command in the
      following sequence.
          Wait one second after sending the
           last item of data
          Type: +++
          Wait one second before typing any
           data
      Do not type the AT prefix or a Carriage
      Return.  The guard time of one second
      before and after the code prevents the
      modem from misinterpreting the presence
      of +++ in the transmitted data stream.
      If necessary, the character used in the
      escape code or the duration of the guard
      time can be changed by resetting
      Register S2 or S12.  See the S-Register
      Summary in Appendix B.
      
Modem Response to +++

      When the modem receives +++, by default
      it enters online-command mode and
      returns the OK result code.  It
      maintains the connection and is ready
      to act on commands.  You may then
      choose one of the following options.
      
          Issue commands to the modem and
           then return it online.  This
           operation is explained below under
           Returning Online.
          Hang up the modem, explained in the
           next section.
      Alternatively, if you want the modem
      automatically to hang up on receiving
      the +++ escape code, set S-Register S14
      to 1 (ATS14=1).  The modem disconnects
      and sends the NO CARRIER result code to
      the screen.
      
Hanging Up (Hn)

      At its default setting, the escape code
      forces the modem into online-command
      mode but leaves the line open.  To hang
      up the modem, issue the following
      command, with or without the zero, once
      the modem sends the OK result code.
             ATH <Enter> [or ATH0 <Enter>]
      H0 Hang up (go on hook).
      H1 Go off hook.
      If you want to issue commands to the
      modem and have it return online, use
      the next option.
      
Returning Online (On)

      After forcing the modem into online-
      command mode with the escape code
      sequence, you can issue commands and
      then toggle the modem back online with
      the O command, as in the following
      example.
             AT Q1 O <Enter> [or AT Q1 O0
             <Enter>]
      O0 Return online (normal).
      O1 Return online and retrain.  If
          errors occur during a non-ARQ
          connection, try this option.  The
          modem returns online and requests
          that both modems resynchronize.
      O2 Return online and shift rates.  If
          errors occur during a non-ARQ, 2400-
          bps connection, and the remote
          modem also supports this O2
          feature, use it to force the modem
          to shift down to 1200 bps for more
          reliable data transfer.  As line
          improvements occur, the modems can
          be forced to shift up again to 2400
          bps:  send the +++ code and, after
          receiving the OK code, send ATO2.
          
         This feature is part of the CCITT
          V.22 bis recommendation, but is not
          commonly implemented.  Make sure
          that the remote modem has the
          capability of shifting between 2400
          and 1200 bps before using this
          option.
          
AUTOMATIC ANSWERING

      The Sportster 14,400 is shipped with DIP
      switch 5 DOWN, Auto Answer suppressed.
      To set the modem to automatically answer
      incoming calls, do one of the following.
      1.Before powering on the modem, set DIP
         switch 5 UP.  When you turn the modem
         on, the modem answers incoming calls
         on the first ring.
      2.When the modem is on, use software
         control.  The following command
         instructs the modem to answer on the
         first ring.  (You can substitute a
         higher value.  See the S-Register Sum
         mary in Appendix B.)
             ATS0=1 <Enter>
      When the modem senses a call coming in,
      it sends the result code RING to your
      screen, goes off hook, and sends the
      remote modem a high-pitched answer
      tone.  If there is no Carrier Detect
      within 60 seconds, the modem hangs up.
      If the connection is made, the modem
      returns a CONNECT result code.  When
      the
      
      call is disconnected by you or the
      remote user, the modem hangs up and
      returns the NO CARRIER code.
      
Suppressing Auto Answer

      To disable Auto Answer, reverse Steps 1
      or 2 above:  set DIP switch 5 DOWN
      before powering on the modem, or set the
      modem to answer on zero rings.
             ATS0=0 <Enter>
             
Manual Answer

      If you've disabled Auto Answer but are
      expecting an incoming data call, use the
      Manual Answer command.  Send the modem
      the following command after the RING
      result code appears on your screen.
             ATA <Enter>
      When the call is disconnected, the modem
      returns to its original state, Auto
      Answer disabled.
      
Points to Remember

      1.You can set the modem to receive
         calls when you're not at your
         computer or terminal.  Load your
         communications software as you
         normally do, and set the modem to
         Auto Answer.  Also set your soft
         ware's file-save function to save
         incoming messages and/or files.
      2.If you've attached your phone so it
         can be used for conventional calls,
         disable Auto Answer when you are not
         expecting incoming data calls.
         Otherwise, your modem may answer the
         phone before you do, greeting a voice
         caller with a high-pitched,
         irritating answer tone.
         
INTERNATIONAL CALLS

      The following commands apply to
      international calls.
      
CCITT/Bell Answer Sequence (Bn)

      To answer international calls, use the
      default B0 setting.
      B0 This setting is required for V.32
          bis modems to answer V.32 bis
          calls.  It also selects the CCITT
          V.25 answer sequence, used outside
          of North America.
         The B0 setting does not affect the
          modem's ability to call or answer
          domestic modems.  It takes slightly
          longer, however, to connect.
      B1 This setting selects the Bell 2225
          Hz answer tone used in the U.S. and
          Canada, but will prevent your modem
          from answering domestic or
          international V.32 bis calls.
          
Guard Tone (&Gn)

      British phone switching systems require
      answering modems to send an 1800 Hz
      guard tone after they send an answer
      tone.  Some other European phone
      networks require a 550 Hz guard tone.
      Guard tones are not used in the United
      States or Canada.
      &G0No guard tone, U.S./Canada.
          Default.
      &G1550 Hz guard tone follows answer
          tone.  Requires B0 setting.
      &G21800 Hz guard tone follows answer
          tone, United Kingdom and some
          Commonwealth countries.  Requires
          B0 setting.
          
Pulse Dial Make/Break Ratio (&Pn)

      This command sets the ratio of the off-
      hook/on-hook (make/ break) interval for
      pulse dialing.  The default sets the
      modem for use in North America.  The
      ratio must be changed if the modem
      is used to dial out in the United
      Kingdom and some Commonwealth countries.
      &P0Make/break ratio, U.S./Canada:
          39%/61%.  Default.
      &P1Make/break ratio, United Kingdom,
          some Commonwealth countries:
          33%/67%.
          
CCITT V.21_300 bps

      Select this option to call or answer
      overseas modems at 300 bps.  In V.21
      mode, the modem answers Bell 103/V.21
      calls, but only originates V.21 calls.
      This option is enabled in Register S27
      with the following command.
             ATS27=1
             
CCITT V.23_1200/75 bps

      Some United Kingdom applications require
      a 1200-bps speed with a 75-bps back
      channel.  This option is enabled in
      Register S34 with the following command.
             ATS34=8

