Chapter 3 - Using Your Wireless Modem; Phone Numbers For The Wireless Modem; Examples Of Useful At Commands; Verifying Signal Strength - Multitech MultiModem iCell User Manual

Chapter 3 – Using Your Wireless Modem

Phone Numbers for the Wireless Modem

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Every wireless modem will have its own unique phone number.
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The phone number may simply be given to you by your wireless service provider or it may be on the SIM card 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 Vista or 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. AT commands for the MultiModem iCells are
published in separate Reference Guides included on the MultiModem CD and posted 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.
AT+CSQ xx Values
0 - 10
11 - 20
21 – 31
99
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 MultiModem has been registered on the wireless network. Using
HyperTerminal, type AT+CREG? for most models. The MTCMR-EV2 does not use this command, see the note below
for an alternative method.
The modem will respond to AT+CREG? in one of the following ways:
Value
0,0
0,1
0,5
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.
MTCMR-EV2 Note:
The second from the final response will either be 'Modem has registered' or 'Modem has NOT registered'.

Checking the Modem's Identity

Use the ATI command (Note: This command is illustrated using the capital letter I after AT)
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Type ATI0 (Note: The command ends in a zero)
The manufacturing data displays.
Multi-Tech Systems, Inc. MultiModem iCell User Guide
Signal Strength Verification – RSSI
Signal Strength
Weak or Insufficient
Average
Exceptional
No signal
Network Registration Verification
Network Registration Status
The modem is not registered on any network
The modem is registered on the home network
The modem is registered on a network and it is roaming
Using a terminal program, sending the command AT!STATUS will return several lines of information.
LED Bars
1 Bar LED is lit
1 Bar and 2 Bar LEDs are lit
1 Bar, 2 Bar, 3 Bar LEDs are lit
No light
21