Multi-Tech Systems MTCBA-G-U-F4 manual Using Short Message Services SMS

Chapter 3 – Using Your Wireless Modem

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.

26 Multi-Tech Systems, Inc. MultiModem GPRS USB Wireless Modem User Guide