TTGO T-Call V1.4 ESP32 Wireless Module SIM Antenna SIM Card SIM800H Module Unsoldered

The TTGO T-Call V1.4 is an integrated ESP32 microcontroller development board with embedded SIM800H GSM/GPRS module, enabling cellular connectivity for IoT and remote monitoring applications. Professional engineers and IoT developers use this module to build standalone cellular communication systems without requiring external modem components. This product solves the critical challenge of integrating wireless connectivity with microcontroller functionality in space-constrained applications, offering a compact all-in-one solution for 2G cellular communication, SMS transmission, and data connectivity.

Product Overview

The TTGO T-Call V1.4 combines the powerful dual-core ESP32 processor with the SIM800H cellular module on a single PCB, eliminating the need for external GSM modems. The ESP32 handles local processing, WiFi connectivity, and Bluetooth functionality, while the SIM800H module manages 2G/GPRS cellular communication over a standard micro-SIM card slot. The board features an integrated antenna connector for external SIM antenna enhancement, improving signal reception in weak coverage areas. The unsoldered variant ships with all components pre-assembled except for specific connection points, allowing developers to customize their integration approach based on project requirements.

This module operates on 5V power supply with integrated voltage regulation, drawing approximately 2A peak current during cellular transmission. The SIM800H supports quad-band GSM frequencies (850/900/1800/1900 MHz), enabling global cellular coverage across most regions. Communication between the ESP32 and SIM800H occurs via UART interface, allowing developers to send AT commands for controlling cellular functions. The board includes a 3.7V lithium battery charging circuit with protection, making it suitable for portable IoT applications. Built-in debugging capabilities through USB serial interface facilitate rapid prototyping and firmware development.

Key Specifications

Specification	Details
Product Type	ESP32 Development Board with Integrated SIM800H GSM Module
Brand	TTGO
Model	T-Call V1.4
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
Microcontroller	ESP32 Dual-Core 240MHz with 520KB SRAM
Cellular Module	SIM800H Quad-Band GSM/GPRS
Operating Voltage	5V USB or 3.7V Lithium Battery
Communication Interface	UART Serial, USB Micro-B
SIM Card Slot	Micro-SIM Card Socket
Antenna Connector	SMA Female for External SIM Antenna
Peak Current Draw	2A during cellular transmission
Battery Charging	Integrated TP4056 Lithium Charger with Protection
Supported Frequencies	GSM 850/900/1800/1900 MHz GPRS Class 12
Data Rate	GPRS up to 85.6 kbps

Key Features

• Integrated SIM800H Module: Eliminates need for external GSM modem, reducing PCB footprint and component count for compact IoT designs
• Dual-Core ESP32 Processor: 240MHz processing capability with 520KB SRAM enables complex local processing and WiFi/Bluetooth connectivity simultaneously
• External Antenna Support: SMA connector allows connection of high-gain SIM antenna for improved cellular signal reception in remote locations
• Built-in Battery Charging: TP4056 lithium charger with protection circuit supports portable applications without external charging modules
• UART Communication: Dedicated serial interface between ESP32 and SIM800H enables reliable AT command protocol implementation
• USB Debugging Interface: Micro-USB port provides serial console access for firmware development and real-time debugging
• Micro-SIM Support: Standard micro-SIM card slot compatible with all major cellular carriers worldwide
• Unsoldered Configuration: Allows customization of connection points based on specific project integration requirements

Applications and Use Cases

• Remote IoT Monitoring Systems: Deploy environmental sensors, temperature loggers, and air quality monitors in locations without WiFi infrastructure using cellular GPRS data transmission
• GPS Tracking Devices: Combine with GPS modules to create real-time vehicle tracking, asset monitoring, and personal safety devices with cellular location reporting
• Industrial Alarm Systems: Implement remote alarm notification systems for factories and warehouses that send SMS alerts and GPRS data to central monitoring stations
• Smart Metering Applications: Build utility meter reading systems that transmit consumption data via cellular network for automated billing and consumption analytics
• Emergency Communication Devices: Create standalone emergency alert systems that function independently of WiFi infrastructure for disaster response and rural connectivity
• Agricultural IoT Solutions: Monitor soil moisture, weather conditions, and crop health in remote farmland with cellular data transmission for precision farming
• Portable Data Logger: Develop battery-powered data acquisition systems that record sensor information and upload via GPRS when cellular coverage is available

How to Use

Begin by inserting a micro-SIM card with active 2G/GPRS plan into the SIM card slot on the board. Connect the TTGO T-Call V1.4 to your computer via the USB micro-B port and install the CP2104 USB-to-UART driver if not automatically detected. Download the Arduino IDE and add ESP32 board support by configuring the board manager with the appropriate JSON URL. Select the TTGO T-Call V1.4 board from the board selection menu and configure the UART pins for SIM800H communication, typically GPIO16 (RX) and GPIO17 (TX). Flash example sketches that demonstrate AT command transmission to the SIM800H module for basic functionality testing such as checking signal strength, sending SMS messages, and establishing GPRS connections.

For optimal cellular reception, attach an external SIM antenna to the SMA connector on the board, particularly in areas with weak signal strength. If using battery power, connect a 3.7V lithium cell to the battery connector and enable the charging circuit through firmware configuration. Implement proper power management by putting the ESP32 into deep sleep mode between data transmission cycles to extend battery life significantly. Use the UART serial monitor at 115200 baud rate to debug AT command responses and troubleshoot connectivity issues. For production deployments, implement error handling routines that manage temporary network unavailability and retry logic for failed data transmissions.

Frequently Asked Questions

What is the difference between TTGO T-Call V1.3 and V1.4?

The V1.4 version includes improved power management circuitry, better PCB layout for reduced electromagnetic interference, and enhanced battery charging protection. The V1.4 also features more stable UART communication between the ESP32 and SIM800H module, resulting in fewer dropped connections and more reliable AT command execution compared to earlier versions.

Can I use this module with 4G/LTE networks?

No, the SIM800H module supports only 2G GSM and GPRS networks. It cannot connect to 3G, 4G, or LTE networks. However, it remains functional in most regions as carriers maintain 2G infrastructure for legacy device support. For 4G capability, consider the TTGO T-Call Plus which features the SIM7600 module, though at higher cost and power consumption.

What power consumption should I expect during GPRS data transmission?

Peak current draw reaches approximately 2 amperes during active cellular transmission, with average consumption around 800mA during data sessions. In idle mode with GPRS connection maintained, the module draws approximately 5-10mA. In deep sleep mode with periodic wake-ups, consumption can be reduced to under 1mA, making battery-powered deployments feasible for applications with intermittent data transmission requirements.

Is soldering required for the unsoldered version?

The unsoldered version comes with all major components pre-assembled and soldered. Specific connection points may require soldering depending on your integration approach, such as battery connector or antenna adapter connections. Most users can operate this board without additional soldering, though basic soldering skills are recommended for custom modifications or battery integration.

How do I send SMS messages using this module?

Use the AT+CMGS command through the UART interface to send SMS messages. First, set the SMS mode using AT+CMGF=1 for text mode, then use AT+CMGS="phone_number" followed by the message text and Ctrl+Z to transmit. The SIM800H module handles the SMS transmission through the cellular network, and you receive confirmation responses indicating success or failure of the operation.

What is the maximum distance for external SIM antenna?

The SMA connector supports standard coaxial cable up to 10 meters in length without significant signal degradation. For longer cable runs, use low-loss coaxial cable rated for RF applications. The external antenna provides approximately 5-7dB gain improvement over the onboard antenna, significantly enhancing reception in weak signal areas such as basements or remote locations.

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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