SIM800L GSM GPRS Module 5V/3.3V TTL with Bluetooth

GSM/GPRS Module with Bluetooth — Quad-Band Cellular for IoT & Embedded Projects

Key Features

• Quad-Band GSM/GPRS Connectivity (850/900/1800/1900 MHz): Global frequency coverage in a single module. Works with UK networks and virtually every GSM network worldwide — no need to check band compatibility before deploying. Voice calls, SMS, and GPRS data from one tiny board.

• Ultra-Compact 25 x 23mm Form Factor: Smaller than a postage stamp. The SIM800L is designed for space-constrained projects where every millimetre counts — wearables, remote sensors, asset trackers, and compact IoT devices where a full-size GSM shield simply won’t fit.

• Bluetooth Integration: Built-in Bluetooth adds short-range wireless alongside cellular connectivity. Use it for local device configuration, sensor data aggregation, or as a fallback communication channel. Dual-mode communication architectures — cellular for long-range, Bluetooth for local — are straightforward to implement.

• Ultra-Low Power Consumption: Sleep mode draws less than 2.0mA. Idle mode (maintaining network registration and monitoring for calls/SMS) sits below 7.0mA. For battery-powered deployments, this is the figure that determines whether your project runs for days or months between charges.

• AT Command Control via UART: Controlled entirely through standard AT commands over a UART serial interface (max 2.8V logic). Over 200 commands cover network management, SMS, voice calls, GPRS data sessions, HTTP client operations, and Bluetooth — all accessible from any microcontroller with a serial port.

• GPRS Data for IoT: TCP/IP stack built in. Connect directly to cloud APIs via HTTP, send JSON payloads, handle token-based authentication — no intermediate gateway needed. Perfect for sensor reporting, remote monitoring, and lightweight IoT data pipelines.

• MicroSIM Socket & IPX Antenna Connector: SIM slot on the underside keeps the footprint minimal. The IPX (u.FL) antenna connector accepts a wide range of external antennas — from the included wire antenna to higher-gain PCB or stubby antennas for better signal in tricky environments.

Product Description

What the SIM800L Does

The SIM800L is a miniaturised GSM/GPRS module that gives your microcontroller project cellular connectivity — voice calls, SMS messaging, and GPRS internet access — in a package smaller than most coins. Wire it to an Arduino, ESP32, STM32, or Raspberry Pi Pico over UART, send AT commands from your code, and your project can send text messages, make phone calls, post data to web APIs, or receive remote commands from anywhere with mobile signal.

It’s the go-to module for hobbyists and makers building IoT projects, remote monitoring systems, GPS trackers, security alerts, and any application where your device needs to communicate without being tethered to Wi-Fi.

Why the SIM800L Specifically

The GSM module market has dozens of options, but the SIM800L has become the default choice for compact, battery-conscious projects for good reason.

Size matters. At 25 x 23mm, the SIM800L is dramatically smaller than the older SIM900 and most competing modules. If your project lives inside an enclosure, strapped to a piece of equipment, or mounted in a location where space is limited, the size difference is the difference between “fits” and “doesn’t fit.”

Power matters more. The sub-2mA sleep current and sub-7mA idle current mean battery-powered projects are genuinely practical. A decent 18650 cell can keep a SIM800L-based sensor node running for weeks in a sleep-wake cycle, reporting data over GPRS at intervals and sleeping between transmissions.

The ecosystem is massive. The SIM800L is one of the most widely used GSM modules in the maker and IoT community. That means extensive Arduino libraries, detailed tutorials, active forum support, and answers to virtually every problem you’ll encounter already exist online. When you hit an issue at 11pm on a Tuesday, someone has already solved it and posted the fix.

What You Need to Know Before Wiring It Up

Power supply is critical. The SIM800L operates on a narrow 3.8V–4.2V supply range (optimal: 4.0V). This is tighter than the older SIM900’s 3.2V–4.8V tolerance. More importantly, the module can spike to 2000mA during GSM transmission bursts — these last only 577ms but they will crash your project if your power supply can’t handle them. A standard Arduino 3.3V pin will not work. You need a dedicated supply capable of delivering 2A peak current at 4V. A TP4056-charged LiPo cell is the simplest solution — a single-cell LiPo sits naturally in the 3.7–4.2V range and handles current spikes well.

Logic levels need attention. The UART interface runs at a maximum of 2.8V. If you’re connecting to a 5V Arduino, you need a level shifter or a voltage divider on the TX/RX lines. Feeding 5V logic directly into the SIM800L will damage it. 3.3V microcontrollers (ESP32, STM32, Pi Pico) can typically connect directly, though checking your specific board’s logic levels is always wise.

An active SIM card is required. The module needs a micro-SIM with an active plan. For UK IoT projects, pay-as-you-go SIMs from providers like giffgaff, Three, or specialist IoT SIM providers work well. Make sure the SIM doesn’t have a PIN lock enabled, or disable it using AT+CPIN before deployment.

Antenna quality affects everything. The included wire antenna works for development and testing, but for deployed projects — especially in areas with weaker signal — a proper external antenna with a ground plane makes a significant difference to signal reliability and registration speed.

Common Power Supply Solutions

This is the single most important design decision for any SIM800L project, so it’s worth covering properly.

Single-cell LiPo battery (3.7V nominal, 4.2V charged): The simplest and most common approach. A LiPo cell’s voltage range (3.0–4.2V) overlaps nicely with the SIM800L’s 3.8–4.2V operating range, and the cell handles 2A current spikes without voltage droop. Pair with a TP4056 charging board for USB charging. This is the recommended approach for portable and remote projects.

Buck converter from 5V: If you’re powering from a USB source or 5V rail, use a buck converter (not a linear regulator) set to 4.0V output. The converter must be rated for 2A continuous — most small buck modules handle this. A linear regulator like the AMS1117 will work at idle but will brownout during transmission bursts due to current limitations.

Supercapacitor buffer: For edge cases where your supply can deliver steady current but not 2A peaks, a 1000µF+ electrolytic or supercapacitor across the SIM800L’s power pins can absorb the transmission burst demand. This is a supplementary measure, not a replacement for proper supply design.

Getting Started — First Power-Up

Getting the SIM800L to register on a network for the first time trips up a lot of people. Here’s the correct sequence:

1. Connect power — apply a stable 4.0V supply capable of 2A peaks. Do not power from the Arduino’s 3.3V or 5V pin.
2. Insert a micro-SIM — ensure PIN lock is disabled and the SIM has credit/an active plan.
3. Attach the antenna — the module will not register without an antenna connected.
4. Wait 3–5 seconds after power-on for the internal oscillator to stabilise.
5. Send AT via serial — if you get back “OK”, the module is communicating. If not, check your baud rate (default is 115200, but 9600 is more reliable for most microcontrollers — use AT+IPR=9600 to set it).
6. Check registration — send AT+CREG? and look for +CREG: 0,1 (registered, home network) or +CREG: 0,5 (registered, roaming). If you get 0,2 (searching), wait and retry. If persistent, check signal with AT+CSQ.
7. The LED tells the story — fast blink (every 1s) means searching for network. Slow blink (every 3s) means registered. Steady blinking every 3s is your “ready to go” indicator.

Best Use Cases for SIM800

IoT sensor nodes and data loggers — read sensor values, transmit to a cloud API over GPRS at intervals, sleep between transmissions. The sub-2mA sleep current makes battery-powered deployments practical. Suitability: excellent.

SMS alert systems — temperature alarms, security triggers, water level warnings, equipment fault notifications. Send a text when a threshold is crossed. Simple, reliable, no internet dependency. Suitability: excellent.

GPS/GSM trackers — pair with a GPS module (NEO-6M, etc.) and transmit location over GPRS or SMS. Vehicle tracking, asset monitoring, pet trackers. Suitability: excellent.

Remote monitoring and control — receive SMS commands to trigger relays, change settings, or request status reports. Farm irrigation, gate controllers, remote equipment management. Suitability: very good.

Voice call alerts for critical alarms — the SIM800L can initiate voice calls for emergencies where an SMS might be missed. Industrial monitoring, lone worker safety, intrusion alerts. Suitability: very good.

Arduino and maker projects — learning cellular communication, building connected prototypes, experimenting with AT commands and GPRS. The massive community and library support makes this the easiest module to learn on. Suitability: excellent.

High-bandwidth data transfer — GPRS maxes out at roughly 85.6 kbps. For applications needing faster data (image transfer, streaming, large file uploads), you’ll need a 4G module instead. Suitability: not suitable.

Applications requiring guaranteed latency — GSM/GPRS has variable latency that depends on network conditions. For real-time control systems or applications needing sub-second response times, a wired or Wi-Fi connection is more appropriate. Suitability: not recommended.

Frequently Asked Questions

What voltage does the SIM800L need?

The SIM800L requires 3.8V–4.2V DC, with 4.0V being optimal. The supply must handle 2A peak current during GSM transmission bursts. A single-cell LiPo battery is the simplest solution — its natural voltage range matches the module perfectly. Do not power the SIM800L from an Arduino’s 3.3V or 5V pin — it will brownout during transmission and cause erratic behaviour.

Can I use the SIM800L with an Arduino?

Yes — it’s one of the most popular combinations in the maker community. Connect the SIM800L’s TX and RX pins to the Arduino via a logic level shifter (if using a 5V Arduino) or directly (if using a 3.3V board). Power the SIM800L from a separate LiPo or regulated 4V supply — not from the Arduino. Use the SoftwareSerial or HardwareSerial library to send AT commands. Extensive Arduino libraries and tutorials exist online.

Where can I buy the SIM800L in the UK?

The SIM800L is available from Kunkune — shipped fast from Oxfordshire via Royal Mail, typically delivered in 1–2 days. No minimum order, free shipping over £25. No customs charges, no waiting weeks for overseas delivery.

The Bottom Line

The SIM800L is the module that put cellular connectivity within reach of every maker, student, and hobbyist. At a few pounds per unit, it delivers voice, SMS, GPRS data, and Bluetooth in a 25 x 23mm package that fits almost anywhere. The power supply needs are specific but well-documented, the AT command interface is straightforward once you’ve sent your first “AT” and seen “OK” come back, and the community support is unmatched in the GSM module world.

For IoT sensor nodes, SMS alerts, GPS trackers, remote monitoring, and Arduino projects that need to talk to the outside world without Wi-Fi — this is where most people start, and for many projects, it’s all you’ll ever need.

SIM800L SMS Tutorial Using Arduino by @SuperbTech