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(Please note that this is the basic AT Command set.  Many modems do NOT conform to this command set.  However, most of these commands remain the same, or similar from modem to modem.)

Quickly Referenced Commands

&An  -  "Originate/Answer Mode Selection"

&Bn  -  "Auto-Retrain Detection"

&Cn  -  "DCD Option"

&Dn  -  "Modem Response to DTR Option"

&Fn  -  "Active Profile/Factory Defaults"

&Gn  -  "Guard Tone Option"

&Jn  -  "Jack Type Selection"

&Kn  -  "Flow Control Selection"

&Ln  -  "Line Type Selection"

&Mn  -  "Communication Mode Selection"

&Pn  -  "Make/Break Ratio for Pulse Dialing"

&Qn  -  "Communications Mode Option Selection"

&Rn  -  "RTS/CTS Option Selection"

&Sn  -  "DSR Option Selection"

&Tn  -  "Test Option Selection"

&V  -  "Active and Stored Configuration Display"

&Wn  -  "Active Profile Write"

&Xn  -  "DTE Transmit Clock Source"

&Yn  -  "Active Profile Read"

&Zn=x  -  "Telephone Number Write"

Verbosely Referenced Commands

&An  -  "Originate/Answer Mode Selection"  -  When in auto-answer mode this option selects originate or answer mode.

    &A0  -  Enables answer mode

    &A1  -  Enables originate mode

&Bn  -  "Auto-Retrain Detection"  -  If poor line or connection quality is detected this option controls auto-retrain.

    &B0  -  Disable auto-retrain (modem hangs up)

    &B1  -  Enable auto-retrain

&Cn  -  "DCD Option"  -  Selects whether DCD option is enabled or not.

    &C0  -  DCD always enabled

    &C1  -  DCD enabled after a carrier signal is detected

&Dn  -  "Modem Response to DTR Option"  -  Interprets the ON to OFF transmission of the DTR signal from the DTE.  This response of this command can be modified by the &Q settings of some modems.

    &D0  -  DTR is assumed to be on

    &D1  -  DTR drop causes the modem back to command mode, but does not drop

    &D2  -  DTR drop causes modem to hang up

    &D3  -  DTR drop causes the modem to be reinitialized

&Fn  -  "Active Profile/Factory Defaults"  -  Sets the values loaded in the active profile to the values that are set in the default profile.

    &F  -  Default profile.  (Works with most all modems)

    &F1  -  Default profile #2  (Works with many modems)

    &F2  -  Default profile #3  (Works with some modems)

&Gn  -  "Guard Tone Option"  -  Sets the modem to transmit a guard tone using v.22/v.22bis.

    &G0  -  Guard tone is disabled

    &G1  -  A 550 Hz guard tone is enabled

    &G2  -  A 1800 Hz guard tone is enabled

&Jn  -  "Jack Type Selection"  -  Selects the phone jack type.

    &J0  -  Selects RJ-11, RJ-41s, or RJ45s

    &J1  -  Selects RJ-12 or RJ-13

&Kn  -  "Flow Control Selection"  -  Selects the flow control options.

    &K0  -  Flow control disabled

    &K1  -  Normally unused (deals with RTS/CTS)

    &K2  -  Normally unused (deals with XON/XOFF)

    &K3  -  Enable RTS/CTS flow control

    &K4  -  Enable XON/XOFF flow control

    &K5  -  Enable transparent XON/XOFF flow control

    &K6  -  Enable unidirectional XON/XOFF flow control

&Ln  -  "Line Type Selection"  -  This option selects the type of line the modem is using.

    &L0  -  Selects public switched telephone network (normal dialup)

    &L1  -  Selects leased line

&Mn  -  "Communication Mode Selection"  -  This command selects the communications mode.

    &M0  -  Asynchronous

    &M1  -  Synchronous connect mode, asynchronous offline command mode

    &M2  -  Synchronous connect mode, asynchronous offline command mode (DTR set to high)

    &M3  -  Synchronous connect mode

&Pn  -  "Make/Break Ratio for Pulse Dialing"  -  Selects the make/break ratio for pulse dialing.

    &P0  -  North America: Selects 39%-61% make/break ratio at 10 pulses per second

    &P1  -  Europe: Selects 33%-67% make/break ratio at 10 pulses per second

    &P2  -  Selects 39%-61% make/break ratio at 20 pulses per second

    &P3  -  Selects 33%-67% make/break ratio at 20 pulses per second

&Qn  -  "Communications Mode Option Selection"  -  Selects the communications mode options sometimes affecting the &Dn command.

   &Q0 -  Asynchronous mode, the serial port speed will follow the connection speed

   &Q1 -  Asynchronous off-line command mode, synchronous connect mode

   &Q2 -  Asynchronous off-line command mode, synchronous connect mode (this option will also have the modem the first number in its directory)

   &Q3 -  Asynchronous off-line command mode (low DTR), synchronous connect mode (high DTR)

   &Q4 -  Auto-synchronous mode

   &Q5 -  Error correction mode

   &Q6 -  Buffered asynchronous mode

&Rn -  "RTS/CTS Option Selection"  -  This command will select the options for RTS/CTS.

   &R0 -  Sets CTS to follow RTS in data mode, RTS wil be ignored in command mode

   &R1 -  Sets CTS forced to high, RTS will be ignored

&Sn -  "DSR Option Selection"  -  This command selects the DSR option.

   &S0 -  Force DSR high

   &S1 -  Force DSR high during handshake and connection

   &S2 -  Force DSR high will connected

&Tn -  "Test Option Selection"  -  Selects the test mode options.

   &T0 -  End test

   &T1 -  Begin a local analog loopback test

   &T3 -  Begin a local digital loopback test

   &T4 -  Allow a remote digital loopback test

   &T5 -  Disallow a remote digital loopback test

   &T6 -  Request a remote digital loopback test

   &T7 -  Request a remote digital loopback test and a self test

   &T8 -  Start a local analog loopback and self test

&V  -  "Active and Stored Configuration Display"  -  Display the active and stored configuration profiles.

&Wn -  "Active Profile Write"  -  Stores the values for the active profile in non-volatile RAM.

   &W0 -  Write active profile into stored profile 0

   &W1 -  Write active profile into stored profile 1

&Xn -  "DTE Transmit Clock Source"  -  This option selects the clock source for DTE transmit.

   &X0 -  Modem

   &X1 -  DTE

   &X2 -  Modem generates the clock with regards to the receiving carrier signal

&Yn -  "Active Profile Read"  -  After a hard-reset this option will restore a stored profile into the active profile.

   &Y0 -  Restore from stored profile 0

   &Y1 -  Restore from stored profile 1

&Zn=x -  "Telephone Number Write"  -  Write telephone number x to location n.