Designing a remote GSM modem management project

Projects General Guidance
1

I want to build a device that will feature a GSM/3G/4G modem (more likely GSM due to LTE modules costs) and give ability to 'talk' to it remotely via TCP/IP messages or HTTP.

So in other words, when the device is powered on, it should run an HTTP server that will enable sending AT commands and receive responses. For this, it should be able to connect to WI-FI network as well (I know this might sound a bit complex/unusual, but please try to understand, the device is not using GSM modem for network connectivity, instead it provides an interface to interact with the GSM module).

Now I am not familiar with Arduino/MCU world at all, though I am familiar with programming (not for embedded) so I believe I will be able to learn necessary skills and implement the software part. But I am lost at the hardware part, mostly.

I would assume I should use a SIMCom sim800/900 based GSM shield. But I read everywhere that GSM modules are power hungry so I will probably need to power it from an external supply. BTW, are there ready made MCUs that feature GSM module (I believe there aren't but)

For the device to be able to connect to the internet I plan to use WI-FI. Should I get a MCU with on board WI-FI (if so, which one that is compatible with Arduino and is inexpensive would be best)? The issue is I obviously don't know end user's WI-FI network credentials, so what is the way around this? I see it as follows: create a new WI-FI network, then the user connects to it and inputs their network name and password, then device connects to it. Is that the right idea or should it be resolved the other way?

I know there are many questions here, but would appreciate if anyone can answer at least some of those.

P.S. Bonus question: how much complication would managing 2 GSM modules by one MCU add, if it is possible at all (would probably involve designing a custom PCB?)? How about 3,4, more?

2

note:

  1. 2G has been or is being switched off in many countries - you may require a 4G modem
  2. a modem can take 2 or 3 amps when transmitting so generally an external power source is required

would recommend an ESP32 which has onboard WiFi Bluetooth classic and BLE - it is supported by the Arduin0 IDE

do you require WiFi and GSM support in the same MCU?

3

I know, however it seems 3G/4G modules cost at least 30-40$, and usually even more. I cannot afford this as of now. Where I live 2g is still being active.

That would be awesome but I think the MCUs that have out-of-the box cellular connectivity without external module have limited availability, if they exist at all.

4

4G modems are two of threetimes the cost of 2G modems so if 2G is available use it for now - you can always upgrade later

I was thinking of PCBs with MCU and modem on board, e.g. lilygo T-SIM7600E/G/SA-H, lilygo t-call-v1-4 SIM800, etc saves interconnecting wires which can be a cause of problems

how will the WiFi and GSM modem work with each other?