Reference Information
Modem Reference Information
214 Corporate Evaluator’s Guide
Modem Reference Information
If your computer has a built-in modem, you can customize the operation of the modem
using AT commands and S-registers. You can do this from Modems (Windows 98) or
Phone and Modem Options (Windows 2000 and XP) in Control Panel, from most
communications software, or by using terminal mode in your software. See “To change
your modem settings“ on page 68.
Note
You should have a good understanding of modems and how they operate before you
change default settings.
This section contains summary information about AT commands, S-registers, and
selected result codes for the built-in modem.
Modem Reference (3Com, US Robotics)
In the following AT command table, default settings are shown in bold. All listed AT
commands except +++, /, and A/ must be preceded by “AT.”
AT Commands (3Com, US Robotics)
Command Function (3Com, US Robotics)
+++ Escape to online command mode (not preceded by AT)
/ Pause (not preceded by AT), 125 ms default
A Answer manually
A/ Repeat last command (not preceded by AT)
D... Dial a phone number and issue other optional commands: 0-9=Dial digit, T=Tone dial, P=Pulse dial, R=Call
an originate-only modem, W=Wait for second dial tone (X2, X4), @=Wait for answer (X3, X4),
(comma)=Pause in dialing, !=Flash switch hook, #=Auxiliary tone dial digit, *=Auxiliary tone dial digit, ;=Stay
in command mode after dialing, $=Wait for calling card bong, &=Wait for calling card bong, “=Dial the letters
that follow.
D$ Display a list of dial commands
DL Redial last number
DL? Display last dialed number
DSn Dial stored number (n=0,1,2,3)
E0 Turn command echo off
E1 Turn command echo on
F0 Turn online echo on
F1 Turn online echo off
H0 Hang up (go on-hook)
H1 Pick up (go off-hook)
I0 Display the 4-digit product code
I1 Display the checksum
I2 Display the RAM test results
