Chapter 3 – Using Your Wireless Modem
24 Multi-Tech Systems, Inc. MultiModem GPRS USB Wireless Modem User Guide
Chapter 3 – Using Your Wireless Modem

Changing the GPRS Band

All MultiModem GPRS-F4 wireless modems support quad band (850/1900/900/1800 MHz). In reality, they operate
like dual, dual-band modems. In other words, they can be configured for 850/1900 or 900/1800 MHz; they do not
auto-seek the local area frequency.

Build Options

The GPRS-F4 wireless modems can be ordered with a default band of 850/1900 MHz or 900/1800 MHz.
850/1900 MHz – The wireless modem defaulting to 850/1900 MHz is identified with F4 in the product ordering
number. Example: MTCBA-G-F4. This build option is most commonly used in North American.
900/1800 MHz – The wireless modem defaulting to 900/1800 MHz is identified with F4-ED in the product ordering
number. Example: MTCBA-G-F4-ED. This build option is most commonly used in Europe.

Changing the GPRS Band

If for any reason, such as changing the geographical area in which you use your modem, you want to change the
band, you can accomplish it by using the +WMBS AT Command.

Steps for Changing the GPRS Band

You must use a terminal application such as HyperTerminal in order to enter the AT Command.
1. To open HyperTerminal, click Start. Then select Programs > Accessories > Communications. Then
click HyperTerminal.
2. When the command window opens, type AT+WMBS=<Band><Param>. Press Enter.
For <Band>. Enter the option you desire:
4 = Dual-band mode 850/1900MHz
5 = Dual-band mode 900/1800MHz
For <Param>, enter the option you desire:
0 = The modem will have to be reset to start on the specified band(s). This is the default.
1 = The modem restarts immediately on the specified band(s).
Example: AT+WMBS=4,0. Press Enter.

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.