4G LTE + SMS module for Microcontroller

[DeadlyChemist]

Hey,

im overwhelmed with the options and im unsure what works/does not

here is my project:
I have a raspberry pi 4B (ubuntu) running quart/flask server at home which allows me to do certains things over the internet, it's the only port forwarded device in my home.
required, this must work:

• I want to add SMS support so I can make request to send/get sms
• my rpi 4b has a case and GPIO is unavailable, however USB is fine
• must use my existing sim card (200mb), however germany disabled 2G/GSM and 3G/UTMS so it must use LTE/4G for communication
• cannot function as alternative network adapter or whatever, 200mb/month would be gone in minutes with the network usage (what i want to say, is that i only wanna make few requests and not pass whole OS to use it freely)

nice to have:

• LTE (more above) support so it can notify me with SMS/API request (i have another API in the cloud) when there is no internet or whatever
• same as above but beeing able to detect no electricity would be sick

what i have

• preffered python, but can figure out any library or langange (im more or less a software dev)
• soldering iron (smd is fine), multimeter
• rpi pico, esp8266, arduino micro? and bunch of parts

before that i used a huawei e3372 stick, but the serial mode would fail, couldn't send a messages, only receive, no http/s calls, had to sepend HOURS writing the software because of the serial loop and AT commands with barely any info online, was unreliable and would just fail. i gave it away

i found this https://www.waveshare.com/pico-sim868-gsm-gprs-gnss.htm but it looks like it won't work FULLY because it does not support 4G?, 2g and 3g are disabled in germany https://www.telefonica.de/news/press-releases-telefonica-germany/2021/12/the-end-of-umts-in-germany-o2-deactivates-last-3g-sites-in-its-network.html

what could i buy? im not looking for anything huge/expensive.
i was also thinking to buy a cheap phone, and write custom software for it, but what would be expensive + take forever tbh.

thanks !

[DeadlyChemist]

I have no idea about the modules, sorry, but if this is already on your LAN/internet
via port forwarding, is there not an online "cloud" API / service / gateway to be able
to send SMSs via. an internet based request?

I am sure I have seen such a feature advertised as parts of various SDKs and cloud platforms, though I don't know how the options work with the carriers that work in Germany.

Having to have / use an LTE adapter and SIM card / account seems a lot of hardware / telecom "investment" only to send a few SMSs.

Oh and to send/get them, at least some while ago when I used it there was for my carrier an SMS to email correspondence so one could send a SMS to an email address and it would be recieved through email, and one could email an email address of the SMS gateway and it would be received by that mobile SMS account.

maybe there is, but 1. i want same number every time, also other services are less reliable than my own
+ i have few services registered on that number, you know, so scammers call that number and go to mailbox, and mailbox is easy to filter from the actual messages i need
the sim card costs me nothing so i wanna keep using that

so yes, i still need module/hardware

[peter-h]

Search for U-BLOX 4G.

Their modules often exist on a board which you can use more readily.

SMS is a basic GSM function, accessible over AT commands, and any such module should support it.

To get onto 4G or whatever, you send it ATDT*99# and that connects you to the network's internet and then your TCP/IP stack has to be connected to the module.

The problem in this business is that the chips or modules have a fairly short life so a design-in today may not be available in a few years' time. Currently I am using a U-BLOX GPS module (NEO-M9N) but that's a different thing. I used Siemens modems for SMS (TC35) but they dropped them, then Cinterion took over, then they dropped them, then somebody else took them over and then dropped them too. So a commercial email2sms service may be easier. But if you are developing a product to sell, people want it integrated so all you need to attach is an antenna.

[RoGeorge]

I see you used capitalization for other acronyms, but you wrote twice 400mb, which reads milibits.  The correct is MB, so 400MB and 400MB/month, which reads 400 megabytes.  Lower letters (mb) milibits doesn't make any sense, caps letters (MB), megabytes is the correct way.   

There's also MiB (mebibytes), which is similar with MB (megabytes), except instead of 1000 multiplier, you have 1024 (2¹⁰) multipliers, so 1MB==1000*1000 bytes, while 1MiB==1024*1024 bytes.

[DeadlyChemist]

Search for U-BLOX 4G.

Their modules often exist on a board which you can use more readily.

SMS is a basic GSM function, accessible over AT commands, and any such module should support it.

To get onto 4G or whatever, you send it ATDT*99# and that connects you to the network's internet and then your TCP/IP stack has to be connected to the module.

The problem in this business is that the chips or modules have a fairly short life so a design-in today may not be available in a few years' time. Currently I am using a U-BLOX GPS module (NEO-M9N) but that's a different thing. I used Siemens modems for SMS (TC35) but they dropped them, then Cinterion took over, then they dropped them, then somebody else took them over and then dropped them too. So a commercial email2sms service may be easier. But if you are developing a product to sell, people want it integrated so all you need to attach is an antenna.

can't find a single one to buy (i live in germany)...
im not looking to sell anything, it's a one off project for myself, need 1 board, have 1 sim
can you link something from aliexpress of ebay or whatever international that will just work?

I see you used capitalization for other acronyms, but you wrote twice 400mb, which reads milibits.  The correct is MB, so 400MB and 400MB/month, which reads 400 megabytes.  Lower letters (mb) milibits doesn't make any sense, caps letters (MB), megabytes is the correct way.   

There's also MiB (mebibytes), which is similar with MB (megabytes), except instead of 1000 multiplier, you have 1024 (2¹⁰) multipliers, so 1MB==1000*1000 bytes, while 1MiB==1024*1024 bytes.

im aware, i just write mb even tho it's incorrect and can't bring myself to remembering it's incorrect

[Scrts]

I am using SIM7070G module form Waveshare: https://www.waveshare.com/sim7070g-cat-m-nb-iot-gprs-hat.htm
Works well in USA with particle.io free SIM card over Cat-M. I've tried it over USB-UART connection on FreeRTOS AWS IoT Windows simulator demo, currently trying to port it to STM32...

I would pick something from Quectel, U-blox or Telit, but SIMCOM modules are cheaper and widely available from China.

Mirror: https://www.amazon.de/-/en/Waveshare-GPRS-Raspberry-SIM7600E-H-Supports/dp/B0892C4GKW/ref=sr_1_2?crid=2DOIEMICUSSXA&keywords=sim7070+g&qid=1656341473&sprefix=sim7070g%2Caps%2C177&sr=8-2

[DeadlyChemist]

I am using SIM7070G module form Waveshare: https://www.waveshare.com/sim7070g-cat-m-nb-iot-gprs-hat.htm
Works well in USA with particle.io free SIM card over Cat-M. I've tried it over USB-UART connection on FreeRTOS AWS IoT Windows simulator demo, currently trying to port it to STM32...

I would pick something from Quectel, U-blox or Telit, but SIMCOM modules are cheaper and widely available from China.

Mirror: https://www.amazon.de/-/en/Waveshare-GPRS-Raspberry-SIM7600E-H-Supports/dp/B0892C4GKW/ref=sr_1_2?crid=2DOIEMICUSSXA&keywords=sim7070+g&qid=1656341473&sprefix=sim7070g%2Caps%2C177&sr=8-2

oh so hooking this up to rpi via usb or esp8266 should be easy
and it works with NORMAL sim cards? think will oder that

or is there something else i need to know?

[Scrts]

I did not try with NORMAL SIM cards, since all those IoT ones still use the regular network providers.
Particle provides 1MB of data monthly for free on their Pilot plan. Enough to send a couple of status bytes couple of times per day...

I remember I had problems with setting up demo code, but apparently the Cat-M frequency settings were set incorrectly. Once I fixed that - everything worked fine.
Another note: you still need to either click a button or use a GPIO to wake-up the module. There might be a 0ohm jumper on the module to do this automatically, but I did not spend time on it...

[DeadlyChemist]

I did not try with NORMAL SIM cards, since all those IoT ones still use the regular network providers.
Particle provides 1MB of data monthly for free on their Pilot plan. Enough to send a couple of status bytes couple of times per day...

I remember I had problems with setting up demo code, but apparently the Cat-M frequency settings were set incorrectly. Once I fixed that - everything worked fine.
Another note: you still need to either click a button or use a GPIO to wake-up the module. There might be a 0ohm jumper on the module to do this automatically, but I did not spend time on it...

i dont need sleep tbh, the few miliamps don't bother me tbh, i prefer FAST sms notification
yeeah, the only question would be, can you try an NORMAL sim card
this is what im using https://www.netzclub.net/

[Scrts]

Check SIM7000E or other variants with your network provider name on google.
I found this: https://schroederdennis.de/allgemein/raspberry-pi-zero-sim7000e-nb-iot-lte-cat-m1emtc-gps/