For Windows users, make sure that you set the correct COM port and IRQ
in your communications software and, if applicable, in Windows Control
Panel > Ports.
Make sure that your communications software is in Terminal mode.
Be sure that your communications software is set to the correct bit
rate and word length (7 bits with or without a parity bit, or 8 bits
and no parity).
Check that DIP switch 8 is ON, for "act on AT commands."
If DIP switch 8 is OFF, power off the modem, set
the switch ON, and power on the modem again. Then
try typing AT and ENTER again.
Make sure that verbal result codes (status messages) are enabled.
Send these commands to the modem:
For your modem to
Command
Enable message display
ATQ0
Display verbal messages
ATV1
Review your communications software manual to see what Carrier Detect
(CD) operations your software requires. Then see the section about Controlling
EIA-232 Signaling.
Although it is a rare condition, check whether your computer is reversing
the send/receive functions at the EIA-232 interface. Refer to your computer's
documentation.
The Modem Won't Dial
If you hear a dial tone when the modem tries to
dial but it quickly returns off hook and reports NO DIAL TONE, try adding
X5 to the dial string. For example, send ATDTX5 5551212 to the modem.
The modem will ignore dial tone detection.
Double Characters are Appearing on Your Monitor
This is a signal that both the modem's local echo
and your software's local echo are on.
Type the command to turn off your online echo (ATF1) or turn your communications
software's local echo off (refer to your software's documentation).
After You Dial, the Modem
Reports NO CARRIER and Then Hangs Up
Try increasing S7 and decreasing S9 to allow more time for the connection.
Try calling a different device. If you are trying to connect to an
older modem at 2400 bps or less, it may not support error control. Try
sending AT&M0, and then try the call again. Reset the modem (send ATZ) after you finish the call.
You Hear Ringing, but the Modem Won't Answer
Look at the DTR LED to make sure that your terminal or computer is
sending a DTR signal via the EIA-232 interface.
Send ATI4 to the modem and check that S0 is set
to a value higher than 0. Also, check that DIP switch 5 is OFF.
Set &F1 and S0=1, then try again.
The Modem Acts as Though
a Data Link Has Been Established, but No Call Was Received
Carrier Detect (CD) may be overridden (with &C0), but your system
may require that the override be turned OFF (with &C1). Review your
communications software manual to see what CD operations are required.
The Modem Behaves as if ENTER
Were Pressed When You Don't Press Any Keys
Your software may be misreading signals from the modem when the modem sends a Carriage Return and
a Line Feed before and after the RING and CONNECT messages. Sending the
Quiet mode command, ATQ1, should solve the problem.