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Chapter 3 – Using Your Wireless Modem
28 Multi-Tech Systems, Inc. MultiModem GPRS USB Wireless Modem User Guide
Examples of Useful AT Commands
Using HyperTerminal
In order to verify signal strength and roaming status, you must use a terminal application such as
HyperTerminal. To open this program in Windows XP, go to Start > All Programs > Accessories >
Communications > HyperTerminal. Other Windows operating systems have similar paths to
HyperTerminal. See your system’s online Help if you cannot find it.
Using AT Commands
AT commands can be used to operate, configure, and query your modem. You can find a reference
guide to the GPRS commands on the Multi-Tech website.
The following two commands let you query signal strength and roaming status.
Verifying Signal Strength
1. Using HyperTerminal, type AT+CSQ
2. The modem responds with the received signal strength (rssi).
RSSI ranges from 0 to 31.
Signal Strength Verification – RSSI
21
–
31 Exceptional
11 - 20 Average
0 - 10 Weak or Insufficient
99 No signal
3. The modem responds with the channel bit error rate (ber).
BER ranges from 0 to 7 (Seven is the highest error rate).
Checking Network Registration and Roaming Status
This section describes how to verify that the wireless MultiModem has been registered on the wireless
network.
1. Using HyperTerminal, type AT+CREG?
2. The modem responds in one of the following ways:
Network Registration Verification
Value Network Registration Status
0,0 The modem is not registered on any network
0,1 The modem is registered on the home network
0,5 The modem is registered on a network and it is roaming
Note: If the modem indicates that it is not registered, verify the signal strength to determine if the
problem is the strength of the received signal.
Checking the Modem’s Identity
Use the ATI command (Note: This command is illustrated using the capital letter i after AT)
● Type ATI0 (Note: The command ends in a zero)
The manufacturing data displays. For example: Wavecom Modem Multiband G850 1900
● Type ATI3
The software version displays. For example: 651_09gg...
● Type ATI6
Displays modem data features. For example: data rates, data modes, fax classes.