I read your discussions about SIM800 / 900 and I have a doubt: Amazon offers modules based on SIM808 / 868 that support 3G and 4G. What is it really this compatibility ?
See https://www.amazon.fr/Sim808-module-développement-antenne-Arduino-Raspberry/dp/B01GFCYYG2 (available on Aliexpress) or https://fr.aliexpress.com/item/SIM868-GSM-GPRS-GPS-BT-CELLULAR-MODULE-MINI-SIM868-board-SIM868-breakout-board-instead-of-SIM808/32827334834.html.
Thanks for help
SIM808 and SIM868 are 2G modules, You wont get 3G and 4G on them, no matter what they advertise.
I need yourn assistance, am working a project. thanks.
If you have business query you can mail me, if you have a technical query you can create a separate thread for your problem.