Chapter 3 – Using Your Wireless Modem
26 Multi-Tech Systems, Inc. MultiModem GPRS USB Wireless Modem User Guide
Establishing a Circuit-Switched Data (CSD) Connection
A Circuit-Switched Data Connection (CDC) makes the wireless modem work similar to a regular analog modem.
You must have CSD service in order to make a CSD call. Note that your wireless provider charges airtime usage
for these connections.
Note: Your cellular provider charges airtime usage for these connections.
Establish a Connection: Using HyperTerminal or a terminal application, you can establish a CSD
connection by entering the following command: ATD<phone number>
Notes:
• The phone number you are calling is entered between the displayed
brackets. Do not type additional brackets. For example, type only ATD
8585551212. 8285551212 is typed between the brackets.
• This command tells the modem to inform the wireless network that you are
initiating a CSD modem call. If you are dialing to another modem, the
remote modem should answer and a connection between the two modems
will be established. If you include a semi-colon (;) at the end of the dialing
string, the modem will instead initiate a Voice call to the phone number
dialed.
Disconnect: Type: +++
Wait about two seconds to see an OK response.
Then type: ATH
Note: +++ is the escape sequence and ATH is the Hang-up command.
Answering a Circuit-Switched Data (CSD) Connection
A Circuit-Switched Data Connection makes the wireless modem work similar to a regular analog modem. You
must have CSD service in order to answer a CSD call.
There are three phone numbers for GSM: the voice number, the data number, and the fax number. All are
provided by the carrier. To answer a call:
Establish A Connection: Call into the modem by dialing the data number provided by your carrier.
Answer a Call: When you see the RING responses on the terminal screen, enter ATA <cr> to
answer the call.
Set Auto-Answer: Enter ATS0=x
This sets the modem to auto-answer. The call will be answered after the number
of rings entered. x stand for the number rings.
Then call into the number provided to you by the carrier.
Disconnect: Type: +++
Wait about one second to see an OK response.
Then type: ATH
Using Short Message Services (SMS) Send a Short Message to a Specified Number.
Type AT+CMGS="8585551212" <press Enter>
Then type your message: Please call me soon. <press ctrl Z>
The modem may respond with +CMGS:<mr> OK
Write a Message to Memory.
You can store a message to send it at a later date.
Type AT+CMGW="8585551212" <press Enter>
Type the message. <press ctrl Z>
The modem may respond with +CMGW: 4 OK (The message is stored in the index as message 4.)
Send a Message from Storage.
Type AT+CMSS=x,"8585551212" <press Enter>
The modem may respond with +CMSS: 1 OK (The transmission is successful. One SMS message is
sent.)
Note: The x represents an index location.