NB-IoT HAT for Raspberry Pi, Based on SIM7020E, B1/B3/B5/B8/B20/B28 Bands Controlled via Serial AT Commands Support LWM2M/COAP/MQTT/TCP/UDP/HTTP/HTTPS, 3.3V/5V

Hi, Many hours of soul searching but was worth it, now fully working with our range of GSM's and a lot faster due to 3g and 4g, we were using just 2g but looking to future proof, tried contacting their support, wouldn't bother if I was you, hardest part was changing baud rates to match, don't bother using cp2102 through usart I have had issues before with the M2M software, I use Ft232rl much better, why ? who knows I'm an end user not the designer ! I have given it a 3 Stars not for the product but the support, the product gets 5 but the support gets 1 hence the 3 !! I'm not using PI or Raspberry so don't ask for help with those I design my own boards and hand shake between sim modules and PIC devices.

It took me a long time to get this working reliably with my Raspberry Pi.When plugged directly onto the Pi it worked but was unreliable which I beleive was due to current limitations. I then unplugged from the and wired it up next to the Pi (this actually suited me as I wanted to git another HAT anyway).The Rx/Tx lines were only 75mm long but the communication was extremely unreliable. One day it would work but another day and I couldn't get a response from the AT command. After I twisted the Rx/Tx wires and the communication became 100% reliable.So, in summary, for best reliability, I found that it worked better if not plugged into the Pi, decent 5V supply direct to the board and twisted Rx/Tx wires.

Needs a fair bit of tinkering to get it to workMost importantFeeding the power to the board not through the pi increased reliability with network connectivity