AT MODEM COMMANDS
   +------------------------------------------------------------------------+
   | COMMAND |                            ACTION                            |
   |---------+--------------------------------------------------------------|
   |         | Enters answer mode. After going off hook, the modem will     |
   | A       | answer the incoming call. It will then go on-line with the   |
   |         | other modem.                                                 |
   |---------+--------------------------------------------------------------|
   | A/      | Previous command line is repeated. Not to be preceded by AT  |
   |         | nor followed by                                              |
   |---------+--------------------------------------------------------------|
   | B0      | Use CCITT V.22 at 1200 bps                                   |
   |---------+--------------------------------------------------------------|
   | B1      | Use 212A at 1200 bps. Not supported in the United Kingdom    |
   |---------+--------------------------------------------------------------|
   |         | When making a call using CCITT V.23, transmit at 75 bps and  |
   | B2      | receive at 1200 bps. When answering and N0, transmit at 1200 |
   |         | bps and receive at 75 bps.                                   |
   |---------+--------------------------------------------------------------|
   |         | When making a call using V.23, transmit at 1200 bps and      |
   | B3      | receive at 75 bps. When answering and N0 selected, transmit  |
   |         | at 75 bps and receive at 1200 bps.                           |
   |---------+--------------------------------------------------------------|
   | B15     | Use CCITT V.21 at 300 bps                                    |
   |---------+--------------------------------------------------------------|
   | B16     | Use 103 at 300 bps. Not supported in the United Kingdom.     |
   |---------+--------------------------------------------------------------|
   | B41     | Use CCITT V.32 at 4800 bps                                   |
   |---------+--------------------------------------------------------------|
   | B42     | Use Express 96 at 4800 bps                                   |
   |---------+--------------------------------------------------------------|
   | B60     | Use CCITT V.32 at 9600 bps                                   |
   |---------+--------------------------------------------------------------|
   | B61     | Use Hayes Express 96 proprietray protocol 9600 bps           |
   |         | connection.                                                  |
   |---------+--------------------------------------------------------------|
   |         | Originate mode. The modem goes off-hook and tries to go      |
   | D       | on-line with another modem. The dial modifiers (see next     |
   |         | table) direct the modem what, when, and how to dial.         |
   |---------+--------------------------------------------------------------|
   | E0      | In command state, characters are not echoed from the         |
   |         | keyboard to the screen.                                      |
   |---------+--------------------------------------------------------------|
   | E1      | In command state, characters are echoed from the keyboard to |
   |         | the screen                                                   |
   |---------+--------------------------------------------------------------|
   | H0      | After hanging up, place modem in command state.              |
   |---------+--------------------------------------------------------------|
   | H1      | After going off hook, operate auxilary relay                 |
   |---------+--------------------------------------------------------------|
   | I0      | Show numeric product code                                    |
   |---------+--------------------------------------------------------------|
   | I1      | ROM checksum is calculated                                   |
   |---------+--------------------------------------------------------------|
   | I2      | ROM checksum is verified (output is OK or ERROR)             |
   |---------+--------------------------------------------------------------|
   | L0, L1  | Speaker volume low                                           |
   |---------+--------------------------------------------------------------|
   | L2      | Speaker volume medium                                        |
   |---------+--------------------------------------------------------------|
   | L3      | Speaker volume high                                          |
   |---------+--------------------------------------------------------------|
   | M0      | Speaker off                                                  |
   |---------+--------------------------------------------------------------|
   | M1      | Speaker on until carrier detected                            |
   |---------+--------------------------------------------------------------|
   | M2      | Speaker on                                                   |
   |---------+--------------------------------------------------------------|
   | M3      | Except when dialing, speaker on until carrier detected       |
   |---------+--------------------------------------------------------------|
   | N0      | Handshake only at rate specified by S37 while originating or |
   |         | answering                                                    |
   |---------+--------------------------------------------------------------|
   |         | Negotiate common communication standard, while originating,  |
   |         | at the optimum line speed supported by both modems.          |
   | N1      | Negotiations start at the DCE line speed specified in S37,   |
   |         | dropping back to a slower speed if required. Go back from    |
   |         | CCITT V.22 to CCITT V.21, when answering.                    |
   |---------+--------------------------------------------------------------|
   |         | Negotiate common communication standard, while originating,  |
   |         | at the optimum line speed supported by both modems.          |
   | N2      | Negotiations start at the DCE line speed specified in S37,   |
   |         | dropping back to a slower speed if required. Go back from    |
   |         | CCITT V.22 to CCITT V.23/CCITT V.21, when answering.         |
   |---------+--------------------------------------------------------------|
   |         | Handshake only at speed defined by S37, when originating. Go |
   | N3      | back from CCITT V.32 to CCITT V.22./212A/CCITT V.22bis,      |
   |         | finally 103, when answering                                  |
   |---------+--------------------------------------------------------------|
   |         | Handshake only at speed defined by S37, when originating. Go |
   | N4      | back from CCITT V.32 to CCITT V.22./212A/CCITT V.22bis,      |
   |         | finally 103, when answering                                  |
   |---------+--------------------------------------------------------------|
   |         | Negotiate common communication standard, while originating,  |
   |         | at the optimum line speed supported by both modems.          |
   | N5      | Negotiations start at the DCE line speed specified in S37,   |
   |         | dropping back to a slower speed if required. Handshake only  |
   |         | at speed defined by S37, when answering.                     |
   |---------+--------------------------------------------------------------|
   | O0      | Enter on-line state                                          |
   |---------+--------------------------------------------------------------|
   | O1      | Enter on-line state. Then start equlaizer retrain sequence   |
   |---------+--------------------------------------------------------------|
   | O3      | Enter on-line state. Then start CCITT V.32bis rate           |
   |         | renogotiation sequence                                       |
   |---------+--------------------------------------------------------------|
   | Q0      | Result codes are returned                                    |
   |---------+--------------------------------------------------------------|
   | Q1      | Result codes are not returned                                |
   |---------+--------------------------------------------------------------|
   | Q2      | Result codes are retruned in originate mode. Result codes    |
   |         | are not returned in answer mode                              |
   |---------+--------------------------------------------------------------|
   | Sr?     | Read and respond with current value of register r. ?         |
   |         | requests the value assigned to that register.                |
   |---------+--------------------------------------------------------------|
   | Sr=n    | Register r is set to n.                                      |
   |---------+--------------------------------------------------------------|
   | V0      | Result codes are shown as numbers                            |
   |---------+--------------------------------------------------------------|
   | V1      | Result codes are shown as words                              |
   |---------+--------------------------------------------------------------|
   | W0      | Negotiation progress messages are not returned               |
   |---------+--------------------------------------------------------------|
   | W1      | Negotiiation progress messages are returned                  |
   |---------+--------------------------------------------------------------|
   |         | Negotiation progress messages are not returned. CONNECT      |
   | W2      | messages are returned with modem-to-modem (DCE) speeds, not  |
   |         | modem-to-DTE speeds.                                         |
   |---------+--------------------------------------------------------------|
   | X0      | Give basic call progress result codes: CONNECT , NO CARRIER  |
   |         | ,and RING                                                    |
   |---------+--------------------------------------------------------------|
   | X1      | Give basic call progress result codes and connection speeds  |
   |         | (for example, CONNECT 2400)                                  |
   |---------+--------------------------------------------------------------|
   | X2      | Give basic call progress result codes, connection speed, and |
   |         | DIALTONE detection                                           |
   |---------+--------------------------------------------------------------|
   | X3      | Give basic call progress result codes, connection speed and  |
   |         | BUSY signal detection                                        |
   |---------+--------------------------------------------------------------|
   | X4      | Give basic call progress result codes connection speed, BUSY |
   |         | signal detection and DIALTONE detection.                     |
   |---------+--------------------------------------------------------------|
   | Y0      | Ignore longspace disconnect                                  |
   |---------+--------------------------------------------------------------|
   | Y1      | Obey longspace disconnect                                    |
   |---------+--------------------------------------------------------------|
   | Z0      | After reset, recall user profile 0                           |
   |---------+--------------------------------------------------------------|
   | Z1      | After reset, recall user profile 1                           |
   |---------+--------------------------------------------------------------|
   | &A0     | When auto-answering, connect as answering modem              |
   |---------+--------------------------------------------------------------|
   | &A1     | When auto-answering, connect as originating mode,            |
   |---------+--------------------------------------------------------------|
   | &C0     | Presence of carrier detect signal is assumed (ROM default.   |
   |         | This value is recalled after &F is issued)                   |
   |---------+--------------------------------------------------------------|
   | &C1     | Track status of carrier detect signal                        |
   |---------+--------------------------------------------------------------|
   | &C2     | Presence of carrier detect signal is assumed until on-line.  |
   |         | From that point, track status of signal                      |
   |---------+--------------------------------------------------------------|
   | &D0     | Status of DTR signal is ignored. (ROM Default. This value is |
   |         | recalled after &F is issued)                                 |
   |---------+--------------------------------------------------------------|
   |         | DTR signal is monitored. The modem enters command state      |
   | &D1     | after an on-to-off transition of DTR signal. If the          |
   |         | connection is intact, the O0 command returns to the on-line  |
   |         | state.                                                       |
   |---------+--------------------------------------------------------------|
   | &D2     | DTR signal is monitored. The modem hangs up and enters       |
   |         | command state after an on-to-off transition of DTR signal.   |
   |---------+--------------------------------------------------------------|
   | &D3     | DTR signal is monitored. The modem hangs up and resets after |
   |         | an on-to-off transition of DTR signal.                       |
   |---------+--------------------------------------------------------------|
   | &F      | Recall factory configuration                                 |
   |---------+--------------------------------------------------------------|
   | &G0     | Guard tones not used (Not supported in Netherlands, Norway,  |
   |         | Sweden, Switzerland, or the United Kingdom)                  |
   |---------+--------------------------------------------------------------|
   | &G2     | 1800 Hz Guard tones are used                                 |
   |---------+--------------------------------------------------------------|
   | &J0     | Configure for RJ-11, RJ-41S, RJ-45S telco jacks              |
   |---------+--------------------------------------------------------------|
   |         | Configure for RJ-12, RJ-13 telco jacks (Not supported in     |
   | &J1     | Netherlands, Norway, Sweden, Switzerland, or the United      |
   |         | Kingdom)                                                     |
   |---------+--------------------------------------------------------------|
   | &K0     | Local flow control disabled                                  |
   |---------+--------------------------------------------------------------|
   | &K1     | RTS/CTS local flow control enabled                           |
   |---------+--------------------------------------------------------------|
   | &K2     | XON/XOFF local flow control enabled                          |
   |---------+--------------------------------------------------------------|
   | &K3     | RTS/CTS local flow control enabled                           |
   |---------+--------------------------------------------------------------|
   | &K4     | XON/XOFF local flow control enabled                          |
   |---------+--------------------------------------------------------------|
   | &K5     | Transparent XON/XOFF local flow control enabled              |
   |---------+--------------------------------------------------------------|
   | &L0     | Set for dial-up mode                                         |
   |---------+--------------------------------------------------------------|
   | &L1     | Set modem for conditioned leased line (private speechband    |
   |         | circuit) mode                                                |
   |---------+--------------------------------------------------------------|
   |         | Go to the X.25 PAD command state of channel n(n=0-3) from    |
   | &On     | the AT command state. The modem will return to the command   |
   |         | state of last channel selected, if a parameter for this      |
   |         | command is not specified.                                    |
   |---------+--------------------------------------------------------------|
   | &Q0     | Communicate in asynchronous mode                             |
   |---------+--------------------------------------------------------------|
   | &Q1     | Communicate is asynchronous mode 1 - Async-to-Sync           |
   |---------+--------------------------------------------------------------|
   | &Q2     | Communicate in asynchronous mode 2 - Stored Number Dial      |
   |---------+--------------------------------------------------------------|
   | &Q3     | Communicate in asynchronous mode 3 - Voice/Data Switch       |
   |---------+--------------------------------------------------------------|
   | &Q4     | Communicate in asynchronous mode 4 - Hayes AutoSync.         |
   |---------+--------------------------------------------------------------|
   | &Q5     | Communicate in error-control mode                            |
   |---------+--------------------------------------------------------------|
   |         | For interfaces requiring constant speed between the DTE      |
   | &Q6     | (computer/terminal) and the DCE (modem), communicate in      |
   |         | asynchronous mode with automatic speed buffering (ASB)       |
   |---------+--------------------------------------------------------------|
   | &R0     | Track CTS according to RTS                                   |
   |---------+--------------------------------------------------------------|
   | &R1     | Assume CTS (ignore RTS)                                      |
   |---------+--------------------------------------------------------------|
   | &S0     | Assert DSR signal always                                     |
   |---------+--------------------------------------------------------------|
   | &S1     | Assert DSR signal before handshake only                      |
   |---------+--------------------------------------------------------------|
   | &S2     | After handshake negotiation, assert DSR signal, but before   |
   |         | CONNECT XXXXX result code is sent to the DTE                 |
   |---------+--------------------------------------------------------------|
   | &T0     | Halt any test in progress                                    |
   |---------+--------------------------------------------------------------|
   | &T1     | Start local analog loopback                                  |
   |---------+--------------------------------------------------------------|
   | &T3     | Start local digital loopback                                 |
   |---------+--------------------------------------------------------------|
   | &T4     | Grant request from remote modem for remote digital loopback  |
   |---------+--------------------------------------------------------------|
   | &T5     | Deny request from remote modem for remote digital loopback   |
   |---------+--------------------------------------------------------------|
   | &T6     | Start remote digital loopback                                |
   |---------+--------------------------------------------------------------|
   | &T7     | Start remote digital loopback with self-test                 |
   |---------+--------------------------------------------------------------|
   | &T8     | Start local analog loopback with self-test                   |
   |---------+--------------------------------------------------------------|
   | &T19    | Find out if RTS and CTS circuits are supported in the DTE    |
   |         | cable                                                        |
   |---------+--------------------------------------------------------------|
   | &U0     | Trellis coding enabled (CCITT V.32 9600 bps only)            |
   |---------+--------------------------------------------------------------|
   | &U1     | Trellis coding disabled                                      |
   |---------+--------------------------------------------------------------|
   | &V      | View active, user profiles, and stored telephone numbers     |
   |---------+--------------------------------------------------------------|
   | &W0     | Write current configuration parameters in memory as profile  |
   |         | 0                                                            |
   |---------+--------------------------------------------------------------|
   | &W1     | Write current configuration parameters in memory as profile  |
   |         | 1                                                            |
   |---------+--------------------------------------------------------------|
   | &X0     | Derive transmit clock signal from modem's internal           |
   |         | oscillator (internal clock signal on pin 15)                 |
   |---------+--------------------------------------------------------------|
   | &X1     | Derive transmit clock signal from attached computer          |
   |         | (external clock signal on pin 24)                            |
   |---------+--------------------------------------------------------------|
   | &X2     | Derive transmit clock signal from receive carrier (slave     |
   |         | receive clock signal on pin 15)                              |
   |---------+--------------------------------------------------------------|
   | &Y0     | Set stored user profile 0 as power-up configuration          |
   |---------+--------------------------------------------------------------|
   | &Y1     | Set stored user profile 1 as power-up configuration          |
   |---------+--------------------------------------------------------------|
   | &Zn=x   | Store phone number x in location n (n=0-3)                   |
   +------------------------------------------------------------------------+

   Note: The modem must be configured for &Q0(unbuffered asynchronous mode)
   for the &T commands to be entered. For &T19 to work, it must be supported
   by the terminal software.