Project Hub /IoT & Connected Devices/Telemetry & Remote Logging/Call and Text using Raspberry Pi and GSM Module

Intermediate

RASPBERRY PI

₹1,500 – ₹5,000

3 – 6 Hours

Partial Kit

Call and Text using Raspberry Pi and GSM Module

Build a custom mobile phone using a Raspberry Pi and a SIM900A GSM module capable of making calls, receiving calls, sending SMS, and reading text messages.

Originally published on CircuitDigest

View original tutorial

Parts You'll Need

This project is sourced from another site, not written by us — this list is our best match of their components against what we stock, not a verified bill of materials. Always check the original blog (linked above) for the actual parts list before buying.

Raspberry Pi 3 - Model B+ 1.4Ghz 64-bit quad-core Processor with 1 GB Ram (Original) Rs. 9,810.00
MB102 Adjustable Breadboard Power Supply Module (3.3V & 5V) for Arduino & Raspberry Pi Rs. 139.00
Jumper Wire 10 Pin Male To Male 20cm Rs. 45.00
Microphone module - Analog Sound Sensor Module for Arduino Rs. 63.00
400 Points Mini Solderless Prototype PCB Breadboard High Quality Rs. 89.00
Jumper Wire 10 Pin Male To Female 20cm Rs. 45.00

Selected: Rs. 0.00

We don't carry yet: LCD (generic / unspecified)
GSM / GPRS SIM800L
Keypad (Matrix)
Potentiometer / Trimpot
Speaker / Audio Amplifier

Browse all components

How It Works

This DIY cellular communication system operates by interfacing a Raspberry Pi 4 Model B with a SIM900A GSM module to interact with cellular networks using a standard SIM card. The system relies on Python software running on the Raspbian Jessie OS to coordinate input and output peripherals. For user interaction, a 4x4 keypad allows input for dialing numbers and typing messages, while a 16x2 LCD display provides visual feedback, contrasted using a 10k potentiometer. Audio capabilities are handled via a connected speaker and microphone, which can be enhanced using an optional audio amplifier circuit for clearer voice transmission during phone calls. The Raspberry Pi communicates with the GSM module via serial communication, sending AT commands to initiate calls, answer incoming calls, and send or receive SMS text messages. Power is distributed to both the Raspberry Pi and the power-hungry GSM module from an external power supply, with a shared common ground to ensure stable logic level communication across the breadboard and connecting jumper wires.

Why Build This

Design and prototype custom IoT communication terminals and remote emergency alerting systems using cellular infrastructure.

Gain practical experience bridging single-board computers with analog audio peripherals and cellular communication hardware.

Deepen undergraduate-level understanding of serial communication protocols and AT command sets used in mobile networking.

Real-World Application

Custom IoT communication devices, remote emergency alerting terminals, DIY cellular gateways, and understanding the fundamentals of mobile network communication protocols.

Skills You'll Learn

Serial communication

UART interfacing

AT command programming

hardware power management

GPIO peripheral control

LCD display interfacing

matrix keypad scanning

Safety Precautions

Ensure correct voltage supply to both the Raspberry Pi and the GSM module, and make sure common ground connections are properly established between the Pi and the GSM module to prevent hardware damage.

Technology Tags

RASPBERRY PI

GSM MODULE

SIM900A

PYTHON

RPI.GPIO

16X2 LCD

4X4 KEYPAD

UART

AT COMMANDS

SERIAL COMMUNICATION

Frequently Asked Questions

Can I use a Raspberry Pi 3 instead of a Raspberry Pi 4 Model B?

Yes, the project data lists compatibility with the Raspberry Pi 3, and the software libraries like RPi.GPIO and Serial function similarly across these hardware revisions.

Why is a separate power supply needed for the GSM module?

GSM modules require a significant amount of current during network transmission spikes that typically exceed the safe power output capacity of a Raspberry Pi GPIO or USB port, making an external power supply necessary to prevent brownouts.

Do I absolutely need the audio amplifier circuit for making calls?

The audio amplifier circuit is marked as optional, meaning basic call functions may work without it, but an amplifier significantly improves speaker and microphone volume and clarity.

Gallery

This page is part of Kitkraft's Project Hub — a curated collection of electronics & robotics projects gathered from the maker community to help students and hobbyists discover and learn to build. Kitkraft does not claim authorship of the original project, and makes no representation as to the accuracy, completeness or safety of third-party source material. The summary and "How It Works" explanation above are AI-generated, rewritten with reference to the original tutorial — not a reproduction of it. Full credit and a direct link to the original source are provided above. If you're the original creator and have a concern about how your work is represented here, please contact us and we'll address it promptly.

Kitkraft Project Hub — curated from the maker community, credited at the source.

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