Use your old hanphone as GSM modem

Posted in AVR, Cellular, GSM, CDMA, Favorite, Project Links
On Monday, August 28, 2006

Some old handphone, such as Ericsson and Siemens kindly has internal GSM Modem and let us communicate with the modem with AT-command via RS-232 cable. AT-Command is standard modem command introduced by Hayes. With this command we can ask our modem to do things such as send and read SMS.

For example:

ATZ  reset modem
AT+CPMS=ME or SMÂ use internal memory or SIM card
AT+CMGR=N read  message N

Note that, though AT-command is a standard, there are some difference in implementation among handphone and GSM modem products.

Riccibitti article ( shows you how make a Remote Control via SMS, based on AVR ATtiny12 and using old Ericsson T10s, T28 or R320 as GSM modem. With his device, it is possible to turn on/off lamps or other peripherals in your home while you are in office, or any place where you can send SMS to your device in home.

Besides as remote control, the device can also be operated as a Remote Monitoring via SMS system. For example, you can connect a door-sensor. When somebody open the door, an SMS will be sent to you about that event.

The software for ATtiny12 is written in assembly. Riccibitti claim the software implement low-power techniques, which extend battery life to more than a year of continued use using AA cells. Of course it is still depends on how many times the device in active mode.

In his site, you can also buy a ready module called TINY PLANET. The Tiny Planet use T28 and R320 which has already encased.

Other implementation of cheap GSM modem can be found in Serasidis site ( He builds 8 ports remote control system via SMS, and also use Atmel AVR, AT90S2313 and use Ericsson T10s, T18 and T28 as GSM Modem.

For Nokia user, there are several handset type you can us an GSM Modem. For example, N6210 is AT GSM enabled. The AT Commands are: (from experts-exchange forum and others)

Communication setting 115200 bps, 8,N,1

AT+CMGF Select message format
AT+CSCA Set Message Center Number (SMSC)
AT+CMGS Send Message to ...

Other commands:

AT+CMGC Send command (SMS)
AT+CMGD Delete message (SMS)
AT+CMGF Message format (SMS)
AT+CMGL List messages (SMS)
AT+CMGR Read message (SMS)
AT+CMGS Send message (SMS)
AT+CMGW Write message to memory (SMS)
AT+CMSS Send from storage (SMS)
AT+CNMI New message indics to TE (SMS)
AT+CESP Enter block mode (SMS)

If you need list of AT Command for Nokia, you can download at

Possible Related Entries:
[Embedded System roll-b]