bps between the modem and the DTE. This result code is disabled by X0.++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++1.2.2     Negotiation Progress MessagesHayes products report special result codes during error-control negotiation. Whether or not these messages are displayed is selected with the W command (not to be confused with the W dial modifier). The factory setting is messages disabled (W0) to avoid conflict with software programs that do not support this additional level of call progress monitoring.Negotiation progress messages are reported in the following order:CARRIERPROTOCOLAUTOSTREAMCOMPRESSIONCONNECTIf AutoStream is not used, no message is reported.40 - CARRIER 300This message indicates that a carrier signal has been detected at 300 bps (modem-to-modem line speed).44 - CARRIER 1200/75This message indicates that a carrier signal has been detected at 1200 bps when transmitting and at 75 when receiving (modem-to-modem line speed).45 - CARRIER 75/1200This message indicates that a carrier signal has been detected at 75 bps when transmitting and at 1200 bps when receiving (modem-to-modem line speed).46 - CARRIER 1200This message indicates that a carrier signal has been detected at 1200 bps (modem-to-modem line speed).47 - CARRIER 2400This message indicates that a carrier signal has been detected at 2400 bps (modem-to-modem line speed).48 - CARRIER 4800This message indicates that a carrier signal has been detected at 4800 bps (modem-to-modem line speed).49 - CARRIER 7200This message indicates that a carrier signal has been detected at 7200 bps (modem-to-modem line speed).50 - CARRIER 9600This message indicates that a carrier signal has been detected at 9600 bps (modem-to-modem line speed).51 - CARRIER 12000This message indicates that a carrier signal has been detected at 12000 bps (modem-to-modem line speed).52 - CARRIER 14400This message indicates that a carrier signal has been detected at 14400 bps (modem-to-modem line speed).66 - COMPRESSION: CLASS 5This message indicates that data compression using MNP Class 5 has been negotiated for the connection.67 - COMPRESSION: V.42BISThis message indicates that data compression using CCITT V.42bis has been negotiated for the connection.68 - COMPRESSION: ADCThis message indicates that data compression using Hayes Adaptive Data Compression has been negotiated for the connection.69 - COMPRESSION: NONEThis message indicates that data compression was not negotiated for the connection.70 - PROTOCOL: NONEThis message indicates that no protocol was negotiated for the connection. A standard asynchronous connection was made.71 - PROTOCOL: ERROR-CONTROL/ LAPBThis message indicates that an error-control connection was negotiated with LAPB protocol. 72 - PROTOCOL: ERROR-CONTROL/ LAPB/HDXThis message indicates that a half-duplex error-control connection was negotiated with LAPB protocol. 73 - PROTOCOL: ERROR-CONTROL/LAPB/AFTThis message indicates that an error-control connection was negotiated using the Hayes Asynchronous Framing Technique. This protocol is used for connections between modems such as Smartmodem 1200 that do not communicate synchronously across the telephone line. AFT enables an error-control protocol to be used.74 - PROTOCOL: X.25/LAPBThis message indicates that an error-control connection using the X.25 protocol was established with a carrier speed of 1200, 2400, 4800, or 9600 bps.75 - PROTOCOL: X.25/LAPB/HDXThis message indicates that a half-duplex error-control connection using the X.25 protocol was established with a carrier speed of 4800 or 9600 bps.76 - PROTOCOL: X.25/LAPB/AFTThis message indicates that an asynchronous error-control connection using the X.25 protocol was established with a carrier speed of 1200 bps. The Hayes Asynchronous Framing Technique was used.77 - PROTOCOL: LAP-MThis message indicates that an error-control connection using the V.42 LAPM protocol was established. 78 - PROTOCOL: LAP-M/HDXThis message indicates that a half-duplex error-control connection using the V.42 LAPM protocol was established. 79 - PROTOCOL:  LAP-M/AFTThis message indicates that an asynchronous error-control connection using the V.42 LAPM protocol was established with a carrier speed of 1200 bps. The Hayes Asynchronous Framing Technique was used.80 - PROTOCOL:  ALTThis message indicates that an errorge indicates that an error-control connection using the V.42 LAPM alternative protocol was established.  This protocol is MNP Classes 2, 3, and 4 compatible.91 - AUTOSTREAM:        LEVEL 1This message indicates that Hayes AutoStream Level 1 has been negotiated for the connection. This technique provides for multiplexing of multiple virtual channels.92 - AUTOSTREAM:        LEVEL 2This message indicates that Hayes AutoStream Level 2 has been negotiated for the connectionsage indicates that Hayes AutoStream Level 2 has been negotiated for the connection. This technique provides for multiplexing of multiple virtual channels, with transparent control of one PAD (non-simultaneous). Level 3 has been negotiated for the connection. This technique provides for multiplexing of multiple virtual channels, with transparent control of all PADs (simultaneous).93 - AUTOSREAM          LEVEL 3This message indicates that Hayes Autostream Level 3 has been negoitiated for the connection. This technique provides for multiplexing of multiple virtual channels, with transparent control of all PADs (simultaneous). ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++S95     Negotiation Message OptionsS95 enables various result codes that indicate the sequence of events in the establishment of an error-control connection. This register does not affect the way in which the modem negotiates the connection; it merely enables message options. The factory setting for this register is value 0, no bits selected. To enable any combination of the bits, add the value(s) to the right of the bit number and set the register to this sum.Note: The bit values of S95 may be set to override some of the characteristics of the Wn command. Setting any of the S95 bits to "1" enables the corresponding result codes regardless of the Wn command in effect. Changing the Wn command setting does not affect the value set for this register.Bit   Value    Explanation------------------------------------------------------------------------0     1        Verbose CONNECT result code indicates the DCE speed                (rather than DTE speed). Numeric result codes are also                different when CONNECT reports DCE speed.1     2        Append "/ARQ" to CONNECT result code when an                error-control connection is made.2     4        Add CARRIER messages3     8        Add PROTOCOL messages4     16       Add AUTOSTREAM messages5     32       Add COMPRESSION messages------------------------------------------------------------------------For example, if you want to add the compression result code (with W1 selected), you would select bit 5 (value of 32). The command line ATS95=32J<CR> will then enable the COMPRESSION negotiation messages.Refer to the Wn and Xn commands for additional and related information. ========================================================================APPENDIX D:  APPLICATION SUGGESTIONSThis appendix offers suggestions for developing applications software using the Hayes Standard AT Command Set. The techniques described apply to Hayes modems in general except where specifically indicated. Although provided here, this information is intended for experienced programmers who want assistance in modem application development.************************************************************************D.1  Modem IdentificationThe initial concern for most communications software is modem identification. Before the software determines the type of modem (e.g., is it a Hayes modem, a high-speed modem, what features does it support -error-control or compression?). By limiting the AT command controller portion of the software to work with a known set of modems, you can limit the complexity of your software.Because the type of modem that will be present, certain assumptions can be made regarding modem characteristics, such as maximum transmission rate, support of AT commands or specific commands such as L or X. If a more general application is being designed for an environment about which assumptions cannot be made regarding type or brand of modem that might be used, the software's first task should be to identify the modem.The I0 and I4 command options make this process simple. In the initial versions of Smartmodem 1200, I0 returned the three digit response: 120. Since then, responses have been extended for several groups identifying modem supporting 2400 bps, 9600 bps, and other products. The I0 response simply indicates the speed category of the modem.The result of the I0 command is a number which identifies the category of modem product. Some unique I0 values can be used to identify a unique product which has specific behaviors. 960, for example, identifies a Hayes product capable of 9600 bps, which has additional commands and behaviors.The I4 command provides a reliable means of communicating specific features and modulation protocols to software. The responses to the I4 command are strings delimited by <CR> and beginning with a lowercase letter and typically followed by a hex-character bit-map. The I0 and I4 responses currently defined are detailed in the description of the I4 command in Chapter 1.  The tables show the decoding of the hex-map returned in the "a", and "b" bit-mapped strings. If I4 is used to identify features of the modem, consider that new result strings are periodically defined that may be returned in addition to those expected. Fields once designated as "reserved" that held a zero may now have values assigned. The strings themselves may also be of different lengths than previously implemented.In spite of the modifications to this command necessary to be current with new modems, the I4 command is the best way for software to determine the modem type and capability, if the guidelines below are considered:*  I0 or I4 commands should be issued at 1200 bps. All Hayes products (including the Smartmodem 300) respond to AT commands at 1200 bps. Most other brands also respond at 1200 bps. You can switch to a higher transmission rate once the modem has been identified.*  Result codes should be parsed as strings surrounded by <CR><LF>. The string will begin with a lower-case letter followed by up to 39 additional characters.*  After all result strings have been sent, an OK result is returned that obeys the V and Q command settings.*  ERROR, OK, or a numeric result in response to the I4 command should be expected. These results may be returned by products shipped before the I4 command was introduced, or by non-Hayes products.*  The length of the strings may be different than anticipated. If shorter than expected, empty positions should be presumed zeros. If longer than expected, extra characters should be ignored.*  Some non-Hayes brand modems return unpredictable results in response to I0 or I4 commands. One brand of modem actually responds with its configuration when the I4 command is sent.An example I4 command and response is shown below:                     AT E0 V1 Q0 S0=0 I4 <CR>response:     <CR><LF>a087840C004424<CR><LF>      <CR><LF>bF60410000<CR><LF>      <CR><LF>cUS<CR><LF> J     <CR><LF>m0000000001001FFFF<CR><LF>      <CR><LF>OK<CR><LF> Note: Each I4 result is surrounded by <CR><LF>; not all responses are hex-strings; and some responses may not be expected at all.************************************************************************D.2  Result Code RecognitionModems that are equivalent to Hayes modems support verbose and numeric forms of result codes. Unless echo may be a problem and you will be installing the controller in a limited-growth environment, verbose