GSM / GPRS Modules











SIM900A GSM Modem – Serial TTL (RX & TX)


SIM900A is a complete dual band GSM/GPRS solution. We have designed ready to use GSM Modem using this module with its simple serial TTL interface. This Modem featuring an industry standard interface. It delivers GSM/GPRS 900/1800MHz performance for voice , SMS, Data and Fax in small form factor and low power consumption.

Note : Package included with Antenna &  SMA Connector as in above picture


  • Dual Band 900/1800 MHz
  • GPRS Multi-Slot class 10/8
  • GPRS Mobile station class B
  • Compliant to GSM Phase 2/2+
  • Class 4 (2W @900 MHz)
  • Class 1 (1W @1800 MHz)
  • AT commands (GSM07.07,07.05 & SIMCOM enhanced AT Commands)
  • SIM application tool kit
  • Direct connection to microcontroller


  • Security & Surveillance system
  • Smart home system
  • Data logging & transfer system
  • Water pump control system
  • Robot control system

Modem Specification

  • Supply Voltage Range : 7V to 38V
  • Operation Temperature : -40 to +85 Degree C



PIN Information

DBX_RXD Debug Receiver
DBX_TXD Debug Transmitter
SPK_N Speaker Negative
SPK_P Speaker Positve
MIC_N Microphone Negative
MIC_P Microphone Positive
VDD_EXT VDD External
5V 5 Volt Supply (OUT)
GND Ground
RX TTL Receiver
TX TTL Transmitter
RTS Request to send
CTS Clear to send
RI Ring
PWR_KEY Power Key
Status Status


for more info :