HiLetgo Smallest SIM800L GPRS GSM Breakout Module Quad-Band 850/900/1800/1900MHz SIM Card Slot Onboard with Antenna 3.7~4.2V

Works great! Used a dc to dc buck converter to regulate to 4.4 volts, and a micro pro to drive it. Make sure you have tmobile or else 2g wont work in the usa. All other carriers do not work as they dropped 2g networks. 2g support for tmobile will be dropped December 31st 2020 so after that this will not work..

This was my first-ever GPRS GSM board. Note that you'll need a SIM card and cell phone service. Note that if you are interested in medium-distance communication, that LoRa may be a useful alternative which does not require cellular service or a SIM card. The card needed is the "Mini" SIM, smaller than the full size, old school SIMs, and larger than the MicroSIMs (although most Micro Sims come with adapters)At least one reviewer claimed to receive a humidity sensor. I can confirm mine was actually a GPRS GSM board, just as pictured.As with many devices, Adafruit has an excellent online tutorial to help get started. Note that Adafruit stated that "In the US, AT&T no longer sells 2G SIMs! We suggest T-Mobile or T-Mobile distributors", As well as: "The 'H differs from the 'L in supporting bluetooth and fax. Otherwise its the same". There's also no text to speech on the L version.In short, this is an excellent, low-cost board to be introduced to the world of GPRS GSM communications

My module does not work, it attempts to connect to a cell network but cannot, red LED flashes 1 HZ for about 10 sec, stops and restarts. I can send AT commands to the unit and responses received.This unit will not power up with anything less that 4.6 volts, and it draws 0.35 amps--and gets very hot after a few minutes. This happens even with nothing other that power connected.I have a similar SIM800L from a different manufactuter and it fires right up, connects to cell network, draws 50 mA and runs very cool.I can only assume this unit is defective.

We purchase multiple modules at different times but could not get any to work. We kept receiving an error that the SIM card wasn't there. Searches on the internet and Amazon blamed the modules as being faulty and said you can order 10 and find 4 good ones. We eventually found out that we were inserting the SIM card in backwards..... OOPS! Flipped them around and everything was good. Module seems to be pretty good for the price

Works perfectly

Bueno

I purchased this without any research, just thought it would be cool to connect my projects online via mobile. When I made my connections to the board I am using I thought I was ready! (wrong)... I had no idea how fragile sim cards were and the board that powers them. I purchased a buck converter and more units as I was ready to fry! I got the unit working @ "4.3v" more like 4.1ish with load."Specs"Sim: Google FiBuck Converter: B07WQJ2GD610k from board GPIO to SIM800L

Looks like a roll of the dice with this supplier's SIM module quality.The module's LED is blinking once every three seconds, signifying that it is ready for action, but it does not respond promptly to AT commands.I did get it to send a couple of SMS, but it took 8 minutes to send a single SMS. By comparison, Adafruit's version of this module takes mere seconds to execute the same code and send the SMS.