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Chapter 2 – Activation and Installation
Multi-Tech Systems, Inc. MultiModem GPRS USB Wireless Modem User Guide 21
Chapter 3 – Using Your Wireless
Modem
Phone Number for the Wireless Modem
• Every wireless modem will have its own unique phone number.
• The wireless modem’s phone number may simply be told to the subscriber or be on the SIM or both.
Wireless provider implementations may vary.
Examples of Useful AT Commands
A Note About 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.
A Note About AT Commands
AT commands can be used to operate, configure, and query your modem. A reference guide to the GPRS commands
is included on the MultiModem CD and on the Multi-Tech Web site.
The following two commands let you query signal strength and roaming status.
Verifying Signal Strength
Using HyperTerminal, type AT+CSQ
The modem responds with the received signal strength (rssi).
The modem responds with the received signal strength (rssi) and the channel bit error rate (ber).
RSSI ranges from 0 to 31.
Signal Strength Verification – RSSI
21 – 31 Exceptional
11 - 20 Average
0 - 10 Weak or Insufficient
99 No signal
BER ranges from 0 to 7 (Seven is the highest error rate).
Checking Network Registration and Roaming Status
In this procedure, you will verify that the Wireless MultiModem has been registered on the wireless network.
Using HyperTerminal, type AT+CREG?
The modem will respond 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.