GSM Modem SIM 900A
GSM Modem SIM 900A
GSM Modem SIM 900A
The GSM Modem SIM 900A is a compact cellular communication module that enables devices to send and receive SMS messages, make voice calls, and establish GPRS data connectivity over GSM networks. Electronics engineers, IoT developers, and industrial automation professionals use this module to add wireless communication capabilities to embedded systems, remote monitoring devices, and alarm systems. It solves the critical problem of enabling real-time, long-distance communication in applications where WiFi infrastructure is unavailable or unreliable.
Product Overview
The SIM 900A operates on dual-band GSM frequencies (850/900/1800/1900 MHz), allowing global network compatibility across most carriers in India and internationally. The module communicates with microcontrollers via serial UART interface using AT commands, making integration straightforward for developers familiar with embedded systems. It features an onboard SIM card slot that accepts standard 2G GSM SIM cards, eliminating the need for external SIM holders. The module includes a built-in power management system with voltage regulation, protecting your circuit from power fluctuations while maintaining stable operation even during high-current transmission bursts.
What distinguishes the SIM 900A is its proven reliability in industrial applications combined with minimal power consumption in idle mode (approximately 1.5mA standby current). The module supports both voice and data transmission, making it versatile for applications ranging from simple SMS-based alerts to complex IoT data logging systems. Its compact form factor (24mm x 24mm x 3mm) allows integration into space-constrained designs, while the standard 0.1-inch header pins facilitate rapid prototyping and integration with breadboards and PCBs. The module has been extensively tested in harsh environmental conditions and maintains consistent performance across temperature ranges of -40°C to +85°C.
Key Specifications
| Specification | Details |
| Product Type | GSM/GPRS Cellular Communication Module |
| Brand | SIM900A (Standard Module) |
| Origin | Original/Authentic |
| Warranty | 7 days on manufacturing defects |
| Shipping | 1-5 days from Bengaluru |
| Delivery | 7-8 days across India |
| Support | 24/7 via Email and WhatsApp |
| Operating Frequency | 850/900/1800/1900 MHz (Quad-band GSM) |
| Communication Interface | UART Serial (TTL Level, 9600-115200 baud) |
| Power Supply | 5V DC with onboard voltage regulation |
| Current Consumption | Standby: 1.5mA, Transmission: 500mA peak |
| SIM Card Type | Standard 2G GSM SIM Card (Mini-SIM) |
| Dimensions | 24mm x 24mm x 3mm |
| Operating Temperature | -40°C to +85°C |
| Data Rate | GPRS Class 10, SMS, Voice calls |
Key Features
- Quad-band GSM support (850/900/1800/1900 MHz) ensures compatibility with Indian carriers like Jio, Airtel, Vodafone, and BSNL across all network types
- UART serial interface with standard AT command set enables seamless integration with Arduino, Raspberry Pi, PIC microcontrollers, and ARM-based systems
- Integrated SIM card slot eliminates external connectors, reducing PCB complexity and improving reliability in field deployments
- Ultra-low standby current consumption (1.5mA) makes it ideal for battery-powered IoT devices and remote monitoring systems requiring months of autonomous operation
- Built-in power management with voltage regulation protects the module from supply voltage variations common in industrial environments
- Supports simultaneous SMS and data transmission, allowing devices to log data while responding to incoming alerts
- Full voice call capability enables two-way communication for critical applications like emergency alert systems and industrial control
- Compact 24mm x 24mm footprint fits into space-constrained applications including wearables, asset trackers, and portable medical devices
Applications and Use Cases
- IoT Remote Monitoring: Deploy sensors in agricultural fields, water treatment plants, or industrial facilities to transmit real-time data via GPRS to cloud servers, enabling predictive maintenance and resource optimization
- SMS-based Alert Systems: Integrate into home security systems, fire alarms, and industrial equipment to send instant SMS notifications to multiple recipients when critical events occur
- Vehicle Tracking and Fleet Management: Embed in GPS trackers to transmit location coordinates and vehicle diagnostics periodically, enabling real-time fleet monitoring for logistics companies
- Automated Meter Reading (AMR): Implement in smart electricity, water, and gas meters to automatically transmit consumption data to utility providers without manual intervention
- Telemedicine and Health Monitoring: Integrate into wearable health devices and remote patient monitoring systems to transmit vital signs and medical alerts to healthcare providers
- Industrial Control and Automation: Use in PLC systems and industrial controllers to enable remote operation and diagnostics of machinery across geographically distributed locations
- Vending Machine and Payment Systems: Connect payment terminals and vending machines to process transactions and transmit sales data in real-time
How to Use
To integrate the GSM Modem SIM 900A into your project, first ensure you have a valid 2G GSM SIM card from any Indian carrier (Jio, Airtel, Vodafone, BSNL). Insert the SIM card into the onboard slot with the gold contacts facing downward. Connect the module to your microcontroller via UART pins: TX pin to your controller's RX pin, RX pin to your controller's TX pin, and GND to common ground. Apply 5V power to the VCC pin and observe the status LED; a blinking indicator confirms successful network registration. The module communicates exclusively through AT commands sent via serial terminal or your microcontroller code.
Begin communication by sending basic AT commands to verify connectivity: AT (should return OK), AT+CPIN? (checks SIM card status), and AT+CREG? (verifies network registration). Once registered, you can send SMS using AT+CMGS command, receive incoming messages by setting message notification modes, or establish GPRS data connections using AT+SAPBR commands. Configure your microcontroller to handle incoming serial data asynchronously and parse module responses appropriately. For production deployments, implement error handling routines that detect network disconnections and automatically re-register with the network. Always maintain adequate power supply filtering with 100uF capacitors near the module to handle current spikes during transmission, preventing brownouts that can cause unexpected resets.
Frequently Asked Questions
Is the SIM 900A compatible with 4G/LTE networks in India?
No, the SIM 900A is a 2G GSM module and does not support 4G or LTE networks. However, most Indian carriers still maintain 2G GSM infrastructure, so it will function reliably. If you need 4G capability, consider upgrading to modules like SIM7600 or SIM868. For most IoT applications requiring low bandwidth, 2G is sufficient and offers better battery life than 4G alternatives.
What is the maximum distance the module can transmit?
The SIM 900A communicates through cellular towers, so transmission range depends on network coverage rather than the module itself. In urban areas with strong signal, you can reliably communicate across cities. In rural areas, range extends to wherever your carrier has tower coverage. The module's sensitivity is approximately -107 dBm, allowing it to maintain connections with weak signals where other devices might fail.
Can I use the SIM 900A with Jio SIM cards?
Jio primarily operates on 4G/LTE networks and has phased out 2G GSM infrastructure in many regions. While older Jio SIM cards might work in areas with legacy 2G towers, we recommend using Airtel, Vodafone, or BSNL SIM cards which maintain robust 2G GSM networks across India. Always verify 2G coverage in your deployment area before committing to production.
How much data can I transmit using GPRS?
GPRS Class 10 provides theoretical speeds up to 100 kbps, but practical speeds are typically 20-40 kbps. Monthly data limits depend on your SIM plan, not the module. For IoT applications, a typical sensor transmitting 100 bytes every 5 minutes consumes approximately 20-30 MB per month. The module is optimized for intermittent data transmission rather than continuous streaming.
When will I receive my order?
Orders are dispatched within 1-5 business days from our Bengaluru warehouse. Delivery takes 7-8 days to most locations across India.
What is your return and warranty policy?
We offer a 7-day return policy on manufacturing defects only. Contact support within 7 days of receipt for free replacement or full refund. Not applicable for user damage or misuse.
Are bulk discounts available?
Yes, wholesale pricing for orders of 10 or more units. Contact our sales team via WhatsApp or email for a customized bulk quote.
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- Returns: 7-day return policy on manufacturing defects only
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