SIM900 GSM / GPRS Shield for Arduino Uno + Antenna

The GSM / GPRS communication module is based on the SIM900 chip and is used to establish communication in the GSM / GPRS standard. Using the module, you can make a phone call, send and receive SMS, and send data in the GPRS system. There are two Jack 3.5 sockets on the module for connecting headphones and a microphone. The module has an SMA or IPEX antenna socket for connecting an external GSM antenna. The SIM card is placed in the slot also on the module. The module has the basic leads necessary to configure the SIM 900 system using AT commands, data transmission and to power the module. The module has solder pads in which, after soldering pin headers, it can be used as a shield for Arduino UNO.

Pinout:
12 pins GPIOs,
2 PWM pins and built-in ADC in SIM 900 chip (all level 2.8V).
CR1220 battery socket. It is used to maintain the power of the built-in real-time clock.
Communication with the module takes place through the UART port that can work in TTL standard (5V or 2.8V). Using the UART port, AT commands are sent for configuration of the SIM 900 system and for issuing commands. The UART port is also used to transfer GPRS data.

The power supply of the system is in the voltage range of 5 VDC, the current must not be less than 2A.

Technical data:
- Communication in the GSM / GPRS 850MHz, 900MHz, 1800MHz, 1900MHz band
- power supply: 5V-26V (5V 2A recommended)
- current consumption 2A
- UART communication protocol standard 5V and 2.8V (depending on whether solder pads are used next to the microphone jack or pins corresponding to pins D0 and D1 on arduino)
- module dimensions 75 x 55 mm
- sockets for GSM antennas, SMA or IPEX type
Quad-band 850/900/1800/1900 MHz - would work in GSM networks in all countries of the world.

Class 10/8 multi-socket GPRS
Class B mobile GPRS station
Compatible with GSM phase 2/2 +
Class 4 (2 W at 850/900 MHz)
Class 1 (1 W at 1800/1900 MHz)
Control by AT commands - standard commands: GSM 07.07 and 07.05 | Extended commands: SIMCOM AT commands.
Short Message Service - so you can send small amounts of data (ASCII or raw hexadecimal) over the network.
Built-in TCP / UDP stack - enables data transfer to a web server.
RTC support.
Selected serial port.
Loudspeaker and headphone sockets
Low power consumption - 1.5 mA (sleep mode)

Tutorial:
https://randomnerdtutorials.com/sim900-gsm-gprs-shield-arduino/