The Basic Hayes Command Set
The following commands are understood by virtually all modems supporting an AT command set, whether old or new.
| Command | Description | Comments |
|---|---|---|
| A0 or A | Answer incoming call | |
| A/ | Repeat last command | Don't preface with AT, don't follow with carriage return. Enter usually aborts. |
| D | Dial |
Dial the following number and then handshake P - Pulse Dial |
| E0 or E | No Echo | Will not echo commands to the computer |
| E1 | Echo | Will echo commands to the computer (so one can see what one types) |
| H0 | Hook Status | On hook. Hangs up the phone, ending any call in progress. |
| H1 | Hook status | Off hook. Picks up the phone line (typically you'll hear a dialtone) |
| I0 to I9 | Inquiry, Information, or Interrogation | This command returns information about the model, such as its firmware or brand name. Each number (0 to 9, and sometimes 10 and above) returns one line of modem-specific information, or the word ERROR if the line isn't defined. Today, Windows uses this for Plug-and-play detection of specific modem types. |
| L0 or Ln (n=1 to 3) | Speaker Loudness. Supported only by some modems, usually external ones. Modems lacking speakers, or with physical volume controls, or ones whose sound output is piped through the sound card will not support this command. | Off or low volume |
| M0 or M | Speaker off, completely silent during dialing | M3 is also common, but different on many brands |
| M1 | Speaker on until remote carrier detected (i.e. until the other modem is heard) | |
| M2 | Speaker always on (data sounds are heard after CONNECT) | |
| O | Return Online | Returns the modem back to the normal connected state after being interrupted by the "+++" escape code. |
| Q0 or Q | Quiet Mode | Off - Displays result codes, user sees command responses (e.g. OK) |
| Q1 | Quiet Mode | On - Result codes are suppressed, user does not see responses. |
| Sn | Select current register
Note that Sn, ? and =r are actually three separate commands, and can be given in separate AT commands. |
Select register n as the current register |
| Sn? | Select register n as the current register, and query its value. Using ? on its own will query whichever register was most recently selected. | |
| Sn=r | Select register n as the current register, and store r in it. Using =r on its own will store into whichever register was most recently selected. | |
| V0 or V | Verbose | Numeric result codes |
| V1 | English result codes (e.g. CONNECT, BUSY, NO CARRIER etc.) | |
| X0 or X | Smartmodem | Hayes Smartmodem 300 compatible result codes |
| X1 | Usually adds connection speed to basic result codes (e.g. CONNECT 1200) | |
| X2 | Usually adds dial tone detection (preventing blind dial, and sometimes preventing ATO) | |
| X3 | Usually adds busy signal detection. | |
| X4 | Usually adds both busy signal and dial tone detection | |
| Z0 or Z | Reset | Reset modem to stored configuration. Use Z0, Z1etc. for multiple profiles. This is the same as &F for factory default on modems without NVRAM (non volatile memory) |
Note: a command string is terminated with a CR (\r) character
Read more about this topic: Hayes Command Set
Famous quotes containing the words basic, hayes, command and/or set:
“The basic difference between classical music and jazz is that in the former the music is always greater than its performance—Beethoven’s Violin Concerto, for instance, is always greater than its performance—whereas the way jazz is performed is always more important than what is being performed.”
—André Previn (b. 1929)
“We can travel longer, night and day, without losing our spirits than almost any persons we ever met.”
—Rutherford Birchard Hayes (1822–1893)
“An actor must communicate his author’s given message—comedy, tragedy, serio- comedy; then comes his unique moment, as he is confronted by the looked-for, yet at times unexpected, reaction of the audience. This split second is his; he is in command of his medium; the effect vanishes into thin air; but that moment has a power all its own and, like power in any form, is stimulating and alluring.”
—Eleanor Robson Belmont (1878–1979)
“There is nothing less to our credit than our neglect of the foreigner and his children, unless it be the arrogance most of us betray when we set out to “americanize” him.”
—Charles Horton Cooley (1864–1929)