GSM modem / module  - first steps

Please feel free to have a look at GSM FAQ on this homepage as well.

Introduction

These tips should make it easier for you to operate your GSM modem / module. Please read the hints  carefully.

Important AT-Command Sets

Please refer to the manual for the return codes of AT commands. Most of the AT commands  are followed by [Enter]. If not we show it in the examples as below:

Enter PIN

AT+CPIN="xxxx"[Enter]

Give  PIN to the device- important information - enter CPIN  before all other  commands or try to get SIM cards without PIN

Activate saved parameters
ATZ[Enter] Activate user profile

Example: Changing and saving parameters

AT+IPR=2400[Enter] Set transfer rate to 2400 bps
AT&W[Enter] Save parameters to memory

Send and Receive

Example: Data transfer

AT+CPIN="xxxx"[Enter]

Enters PIN

AT+CREG?[Enter]

Register Network (0,1 means logged in)

ATD05111234567[Enter]

Data call

Example: Send SMS with GSM modem / module

Enter SMS-Center

AT+CSCA=+491722270000[Enter]

Enter SMS-Center for Vodafone Germany 
(T-Mobile Germany = +491710760000)

Example: Send SMS

AT+CMGF=1[Enter]
AT+CMGS="+491711234567"[Enter]
>Please call office^Z

+CMGF=1 - Set modem in text mode
Send SMS (^Z equals StrgZ).

Example: Receive SMS

A SMS will be stored in the GSM modem / module and being send via RS232 to the peripherals. The  peripherals have to send commands to the GSM unit to receive SMS and to erase SMS from the  SIM card in order to clean memory.

+CMTI:"SM",x

X stands for the memory number of received SMS

AT+CMGR=X[Enter]

Read SMS on memory number X

AT+CMGD=X[Enter]

Erase SMS on memory number X

Example: Send voice call

AT+CREG?[Enter]

Register Network (0,1 means registered in home network)

ATD05111234567;[Enter]

The only difference to issue a data call and a voice call is the  semicolon. The transmission of any GSM device is digital so the ISDN-profile (bearer type)  is being sent  to the receiving ISDN station. If you dial a ISDN voice device with data transmission,  the ISDN device will not ring!

Important Commands

Note: The answers for networks and field strength can be delayed for several seconds.

ATZ;E[Enter]

Echo OFF

ATZ;E1[Enter]

Echo ON

AT+CSQ[Enter]

Show field strength. Field strength in dBm = -112 dBm+(2*X).  When X gets bigger, then the field strength is higher. -104 dBm is the lowest value for a voice  call. A data calls willfaulty because the noise is to high.

AT+CREG?[Enter]

Answer 0,x (X=2=log off, X=1=log in, X=0=don´t know) please  refer to manual for further infos

AT+COPS?[Enter]

Shows which GSM operators is active.
0,2,26201= T-Mobile  availiable

AT+COPS=?[Enter]

Shows all available networks

 
German version
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