📱 TTGO T-Call SMS Forwarder (Lghnay Project)

A complete IoT solution for forwarding SMS messages to the cloud using the TTGO T-Call ESP32 module with integrated SIM800 GPRS modem. The system captures incoming SMS messages, forwards them to a serverless backend, stores them in a database, and provides real-time email notifications.

🌟 Introduction

Lghnay (Arabic: لغناي) is a robust SMS forwarding system designed for scenarios where you need to monitor SMS messages remotely. Whether you’re tracking verification codes, monitoring alert systems, or simply need remote access to SMS messages, this project provides a complete end-to-end solution.

💡 The Story Behind Lghnay

This project was born out of necessity and a bit of frustration. I had two SIM cards but both backup phones decided to die at the most inconvenient time. Rather than buying yet another phone that might die, the solution was obvious: why not build something better?

With a TTGO T-Call board gathering dust in a drawer and a weekend to spare, Lghnay was born - a dedicated SMS gateway that’s more reliable than those old backup phones ever were. No screens to crack, no batteries to bloat, no operating systems to update. Just a simple, purpose-built device that does one thing well: forward SMS messages to the cloud where they can be accessed from anywhere. Sometimes the best solutions come from the most annoying problems.

Use Cases

• 📲 Remote SMS monitoring and logging
• 🔐 Two-factor authentication code forwarding
• 🚨 Alert system integration
• 🌐 IoT communication gateway

Architecture

The project consists of three interconnected components:

1. Firmware (C++/Arduino): Runs on the TTGO T-Call ESP32, manages the SIM800 modem, and forwards SMS via WiFi
2. Worker (Rust): Cloudflare Workers-based API that receives, stores, and processes SMS data
3. TUI Client (Go): Terminal interface for viewing and managing stored messages

🚀 Features

Firmware

• ⚡ Power management with IP5306 boost control
• 📡 Dual connectivity (GSM/GPRS + WiFi with captive portal)
• 📨 Real-time SMS reception and parsing
• 🔒 Secure HTTPS data transmission
• 🔄 Automatic reconnection handling

Worker API

• 🔐 AES-256-CBC encryption for SMS content
• 🛡️ Custom “Cisab” authentication scheme
• 💾 Cloudflare D1 database integration
• 📧 Email notifications via Resend API
• ⚡ Serverless architecture for scalability
• 🔍 RESTful endpoints for data retrieval

TUI Client

• 🖥️ Clean terminal user interface
• 🔐 Secure API authentication
• 📋 Message listing and viewing
• 🎨 Easy-to-use command-line interface

Encryption Flow

Plain SMS → AES-256-CBC Encrypt → Base64 Encode → HTTPS POST → Server

The worker must decrypt the messages using the same AES key. This ensures that even if someone intercepts the HTTPS traffic or gains access to your Cloudflare account, they cannot read the SMS content without the encryption key.

WiFi Configuration Security

• Uses WiFiManager with captive portal for initial setup
• No hardcoded WiFi credentials in the firmware
• Credentials stored securely in ESP32’s flash memory
• Access point password protects the configuration interface

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📋 Table of Contents

• Hardware Requirements
• Firmware Setup
• Worker Deployment
• TUI Client Usage
• Configuration
• API Reference
• Contributing
• License

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🔧 Hardware Requirements

• TTGO T-Call V1.4 (ESP32 with SIM800C/L modem)
• SIM card with SMS capability (PIN may be required)
• USB cable for programming and power
• WiFi network for internet connectivity

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💻 Firmware Setup

Dependencies

Install the following libraries in your Arduino IDE or PlatformIO:

• TinyGsmClient - SIM800 modem communication
• WiFi (ESP32 standard library)
• HTTPClient (ESP32 standard library)
• Wire (I2C library for IP5306)

Configuration

Create a config.h file in your firmware directory:

// config.h
#define SerialMon Serial
#define SerialAT Serial1

// IP5306 Power Management
#define IP5306_ADDR 0x75
#define IP5306_REG_SYS_CTL0 0x00

// Modem GPIO Pins
#define MODEM_RST 5
#define MODEM_PWKEY 4
#define MODEM_POWER_ON 23
#define MODEM_TX 27
#define MODEM_RX 26
#define I2C_SDA 21
#define I2C_SCL 22

// WiFi Manager Configuration
const char* AP_name = "TTGO-SMS-Gateway";
const char* AP_password = "12345678";  // Access point password (min 8 chars)

// Server Configuration
const char* serverURL = "https://your-worker-url/set";
const char* apikey = "Your_Auth_Token_Reversed";
const char* simPIN = ""; // Leave empty if no PIN required

Upload

1. Connect your TTGO T-Call ESP32 via USB
2. Select ESP32 Dev Module as your board
3. Set upload speed to 115200
4. Upload the firmware
5. First Boot Setup:

• The device creates a WiFi access point: Elghnay_AP
• Connect to it using password: 12345678 (or your configured AP password)
• A captive portal appears automatically (or navigate to 192.168.4.1)
• Select your WiFi network and enter the password
• Click Save - the device will reboot and connect to your WiFi

1. Monitor the Serial output to verify SMS reception and forwarding

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☁️ Worker Deployment

Prerequisites

• Cloudflare Workers account
• Wrangler CLI installed
• Resend API account for email notifications

Environment Variables

Configure the following in your Cloudflare Worker dashboard:

Name	Type	Description
AUTH_KEY	Secret	Un-reversed authentication string
RESEND_API_KEY	Secret	API key for Resend email service
DB	D1 Binding	D1 Database binding name
FROM_EMAIL	Variable	Sender email address
TO_EMAIL	Variable	Recipient email address for notifications
ENCRYPTION_KEY	Secret	Encryption KEY that will be used to encrypt SMS before saving it in DB

Database Setup

Create a D1 database and run the following SQL:

CREATE TABLE messages (
id INTEGER PRIMARY KEY AUTOINCREMENT,
sender TEXT NOT NULL,
sms TEXT NOT NULL,
ts TEXT NOT NULL
);

Deploy

cd worker
wrangler publish

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🖥️ TUI Client Usage

Prerequisites

• Go 1.20+ installed

Running

Set environment variables and run:

export API_URL=https://your-worker-url
export TOKEN=your_reversed_auth_token
go run .

Or build and run:

go build -o ./bin/lghnay-tui
API_URL=https://your-worker-url TOKEN=your_token ./bin/lghnay-tui

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🔐 API Reference

Authentication

All endpoints require the Authorization header with the custom “Cisab” scheme:

Authorization: Cisab <reversed_token>

About “Cisab” Authentication

The name “Cisab” is literally “Basic” spelled backwards - a playful nod to HTTP Basic Authentication while implementing a custom scheme. Instead of the standard Authorization: Basic <base64> header, this project uses Authorization: Cisab <reversed_string>.

How it works:

1. You configure a secret AUTH_KEY in your Cloudflare Worker (e.g., "mySecretKey123")
2. To authenticate, you reverse this key: "321yeKterceSym"
3. Send the reversed key in the Authorization header: Authorization: Cisab 321yeKterceSym
4. The worker reverses it back and compares it to the stored AUTH_KEY

Endpoints

Health Check

GET /health

Returns API status.

Get All Messages

GET /get

Returns all stored SMS messages (newest first).

Get Single Message

GET /get/:id

Returns a specific message by ID.

Store Message

POST /set
Content-Type: application/json

{
"sender": "+1234567890",
"sms": "Message content",
"ts": "2025-10-24 12:00:00"
}

Stores a new SMS message and triggers email notification.

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Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

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License

This project is licensed under the MIT License.