Best Serial Gsm Gprs Modem

Module,Development Board Module Kit,5~26V SIM Development Module,Fit for SIM900 850/900/1800/1900 MHz GPRS/GSM,Quad-Band 850/900/ 1800/1900 MHz - Would Work on GSM Networks

... reason is that the GPRS Shield startup current and the maximum top current required to work up to 2A, but the USB port can not provide such a large current, so the external power supply equipment must be provided..
The other power supply port leads to the 3.7--4.5V power supply for lithium battery power supply. The serial port is perfectly compatible. The TTL serial port is compatible with 3.3 and 5V microcontrollers.Speaker and Headphone jacks..
The best baud rate for GPRS Shield communication is 19200 BPS 8-n-1 (GPRS Shield automatically matches baud rate by default).Quad-Band 850 / 900/ 1800 / 1900 MHz - would work on GSM networks in all countries across the world..
GPRS multi-slot class 10/8.GPRS mobile station class B. Compliant to GSM phase 2/2+. Class 4 (2 W @ 850 / 900 MHz).Class 1 (1 W @ 1800 / 1900MHz).Control via AT commands - Standard Commands: GSM 07.07 & 07.05 | Enhanced Commands: SIMCOM AT Commands..
Short Message Service - so that you can send small amounts of data over the network (ASCII or raw hexadecimal).Embedded TCP/UDP stack - allows you to upload data to a web server.RTC supported.Selectable serial port.Low power consumption - 1.5mA(sleep mode)..

... reason is that the GPRS Shield startup current and the maximum top current required to work up to 2A, but the USB port can not provide such a large current, so the external power supply equipment must be provided..
The other power supply port leads to the 3.7--4.5V power supply for lithium battery power supply. The serial port is perfectly compatible. The TTL serial port is compatible with 3.3 and 5V microcontrollers..
Make sure your SIM card is not locked. The best baud rate for GPRS Shield communication is 19200 BPS 8-n-1 (GPRS Shield automatically matches baud rate by default). Quad-Band 850 / 900/ 1800 / 1900 MHz - would work on GSM networks in all countries across the world..
GPRS multi-slot class 10/8. GPRS mobile station class B. Compliant to GSM phase 2/2+. Class 4 (2 W @ 850 / 900 MHz). Class 1 (1 W @ 1800 / 1900MHz). Control via AT commands - Standard Commands: GSM 07.07 & 07.05 | Enhanced Commands: SIMCOM AT Commands. Short Message Service - so that you can send small amounts of data over the network (ASCII or hexadecimal)..

Mini GSM / GPRS breakout board is based on SIM800L module, supports quad-band GSM/GPRS network, available for GPRS and SMS message data remote transmission..
The board features compact size and low current consumption. With power saving technique, the current consumption is as low as 1mA in sleep mode..
It communicates with microcontroller via UART port, supports command including 3GPP TS 27.007, 27.005 and SIMCOM enhanced AT Commands..
AT command interface with "auto baud" detection..
TTL serial port for serial port, you can link directly to the microcontroller.

SIM800L GPRS GSM module micro SIM core board quad-band TTL serial port is ESP8266 ESP32.

Quad-Band 850/900/1800/1900 MHz - could work on GSM networks in all countries around the world, work with Uno Mega.
Embedded TCP / UDP stack - allows you to upload data to a Web server | RTC supported | selectable serial port | Jac speakers and headphones.
Note: This is a new version (64M version), SMS support MMS: Multimedia message and Short Message Service - so it is possible to send small amounts of data over the network (ASCII or raw hexadecimal).
The shield allows you to get SMS, MMS, GPRS and audio via UART by sending AT commands (GSM 07.07, 07.05 and SIMCOM enhanced to commands). The shield also has the 12 GPIOs, 2 PWMs and an ADC of the SIM900 module (They are all 2V8 logic) present on board..
Application: M2M (Machine 2 Machine) Applications.Remote control of appliances.Remote Weather Station or Wireless Sensor Network.Vehicle tracking system with a GPS module.Good to learn GSM / GPRS mobile phone development, control development of remote equipment, wireless meter reading, smart appliances, ultra long distance control, etc..

...Routing, VPN (PPTP, L2TP, IPSEC, GRE. Suppots WIFI, Compatible with 802.11b/g/n, AP and Client Mode.
Yeacomm Dual SIM 4G Modem supports RS232 (or RS485/RS422), Ethernet port and WIFI that can conveniently and transparently connect one device to a cellular network, allowing you to connect to your existing serial, Ethernet and WIFI devices with only basic configuration.
4G Wireless Industrial Router working band, LTE FDD: B1/2/B3/B4/B5/B7/B8/B28.
HSPA+/HSUPA/HSDPA/WCDMA/UMTS 2100/1900/900/850MHz.
EDGE/GPRS/GSM 1900/1800/900/850MHz. Not compatible with Verizon and Sprint.
Yeacomm 4g lte sim router adopts high-powered industrial 32-bits CPU and embedded real time operating system. Widely used on machine to machine fields, such as self-service terminal industry, intelligent transportation, smart grid, industrial automation, telemetry, finance, POS, water supply, environment protection, post, weather, etc.
Yeacomm YF325 4G Modem Good to use in North America and South America, Australia, New Zealand, Philippines, etc.Gift: 4 in 1 Converter Kit SIM Card Adapter with Steel Tray Eject Pin.