SIM800L GSM/GPRS Module
Compact cellular module for SMS, calls, and GPRS data.
A compact quad-band GSM/GPRS module enabling SMS alerts, calls, and basic cellular data connectivity from a microcontroller. Built around SIMCom's SIM800L chipset, it's smaller and more power-efficient than the older SIM900A while covering all four common GSM frequency bands, making it the more popular default choice today for SMS-notification systems, remote monitoring, and IoT projects that need cellular connectivity without Wi-Fi.
Specifications
| Chipset | SIMCom SIM800L quad-band GSM/GPRS module |
| Frequency bands | Quad-band 850/900/1800/1900MHz, broad global carrier compatibility |
| Operating voltage | 3.4V–4.4V DC (breakout boards commonly regulate from a 5V input, but still require a supply capable of ~2A current spikes) |
| Operating current | ~epsilon current in sleep mode, average ~70mA idle-registered, spikes up to ~2A during transmit bursts |
| SIM card | Micro-SIM card required (2G network only) |
| Functions | SMS send/receive, voice calls, basic GPRS data (2G only — no 3G/4G support) |
| Interface | UART, controlled via standard AT command set |
| Form factor | Very compact compared to the SIM900A, popular for space-constrained builds |
Pinout
| Pin | Name | Description |
|---|---|---|
| 1 | VCC | Power — requires a stable regulated 3.7-4.2V supply capable of ~2A peak current, NOT a standard 5V logic rail directly |
| 2 | GND | Ground |
| 3 | TX | UART transmit — connect to microcontroller RX |
| 4 | RX | UART receive — connect to microcontroller TX (3.3V logic level, use a divider from 5V boards) |
| 5 | RST | Module reset pin, active LOW |
| 6 | SIM slot | Micro-SIM card holder on the underside of the board |
| 7 | NET | Antenna connector — an external GSM antenna is essential for reliable signal |
The SIM800L's power requirement is the single most common source of problems: it needs a dedicated 3.7-4.2V supply (often from a LiPo battery or a beefy buck converter) able to deliver short ~2A current spikes during transmit — powering it directly from an Arduino's 5V pin will cause random brownouts and resets. RX is 3.3V logic level and should be level-shifted or divided down from 5V microcontrollers.
Variants
For a first project, the version with an onboard regulator/level-shifter board is worth the small price premium since it eliminates most of the power-related reliability issues that plague bare SIM800L breakouts. As with the SIM900A, confirm 2G availability in your area before committing, since carriers are progressively shutting it down.
| Variant | Temp range | Hum range | Accuracy | Protocol | Price |
|---|---|---|---|---|---|
| SIM800L (bare breakout) | ~$3-6 | ||||
| SIM800L with onboard regulator/level-shift board | ~$5-9 | ||||
| SIM7600 series | ~$15-30 |