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Owing to our vast industrial experience, we are dedicatedly involved in supplying and trading a comprehensive array of GSM/GPRS for SMS based Remote Control & Alerts, Security Applications, Sensor Monitoring, GPRS Mode Remote Data Logging, Bulk Sms Application and many more. The offered range is strictly in adherence with the predefined quality standards and widely reckoned in the market for its hi-end technological features & advantages. Further we offer GSM/GPRS Modem Such as GSM/GPRS Sim900a Modem RS232, GSM/GPRS Q2686A Wavecom Modem, GSM/GPRS Q2403 Wavecom Low Cost Modem, GSM/GPRS Q2406 Wavecom Modem.

GSM/GPRS Modem - SIM900A - RS232

GSM/GPRS Modem - SIM900A - RS232

Item Code: Sim900A-RS232

Description: This GSM/GPRS Sim900a Modem-RS232 is built with Dual Band GSM/GPRS engine- SIM900A, works on frequencies 900/ 1800 MHz. The Modem is coming with RS232 interface,which allows you connect PC as well as microcontroller with RS232 Chip(MAX232). The baud rate is configurable from 9600-115200 through AT command. The GSM/GPRS Modem is having internal TCP/IP stack to enable you to connect with internet via GPRS. It is suitable for SMS, Voice as well as DATA transfer application in M2M interface. Using this modem,you can make audio calls, SMS, Read SMS, attend the incoming calls and internet ect through simple AT commands.


  • SMS based Remote Control & Alerts
  • Security Applications
  • Sensor Monitoring
  • GPRS Mode Remote Data Logging


  • Status of Modem Indicated by LED
  • Simple to Use & Low Cost
  • On board switching type power supply regulator
  • RS232 output
  • SMA connector with GSM Antenna.
  • Input Voltage: 5V-12V DC

SIM800 Quad Band GSM/GPRS Serial Modem with FM and Bluetooth

SIM800 Quad Band GSM/GPRS Serial Modem with FM and Bluetooth

The SIM800 modem has a SIM800 GSM chip and RS232 interface while enables easy connection with the computer or laptop using the USB to Serial connector or to the microcontroller using the RS232 to TTL converter. Once you connect the SIM800 modem using the USB to RS232 connector, you need to find the correct COM port from the Device Manger of the USB to Serial Adapter. Then you can open Putty or any other terminal software and open an connection to that COM port at 9600 baud rate, which is the default baud rate of this modem. Once a serial connection is open through the computer or your microcontroller you can start sending the AT commands. When you send AT commands for example: "AT " you should receive back a reply from the SIM800 modem saying "OK" or other response depending on the command send.


Important Note:

  • The SIM800 requires huge power, so use a 12V DC 2 to 3 Amps adapter, any wrong adapter might cause damage also to the modem.
  • On the board there are Tx(D) and Rx(D) pins, near the 5V and GND pins, don't ever connect anything to them or send any command to them, they are not the TTL pins for serial communication, they are for upgrading the firmware, and if you connect them to the microcontroller or computer, the firmware will get damaged and the module will stop working.
  • Please read carefully the marking on the SIM card tray on how to open or close, those are made of brittle plastics and will break if you put too much pressure on them, so be very gentle and careful while removing or inserting SIM Cards.
  • Don't tight the antenna too much, the screw threads might get damaged by excessive or over tightening of antenna.
  • Please don't touch the connections or components and always put the modem on a non conductive base.


Rajguru Electronics
Dileep Jain (Manager)
399 3rd Floor , Manek Chambers , Above Vasant Bhavan Restaurant , Lamington Road,
Mumbai - 400004, Maharashtra, India

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