Chapter 3 - Using Your Wireless Modem; Phone Numbers For The Wireless Modem; Examples Of Useful At Commands; Verifying Signal Strength - Multitech MultiModem Cell MTCBA-E1 User Manual

Phone Numbers for the Wireless Modem

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Every wireless modem has a 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
Cells are published in separate Reference Guides 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.
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?
The modem will respond in one of the following ways:
Value
0,0
0,1
0,5
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.
Multi-Tech Systems, Inc. MultiModem Cell User Guide
Signal Strength Verification – RSSI
AT+CSQ xx Values
0 - 10
11 - 20
21 – 31
99
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
Signal Strength
Weak or Insufficient
Average
Exceptional
No signal
24