Azure over PPPos

I like to connect to Azure over pppos (Sim800l or so) instead over wireless lan.
Is there an example that shows, how this must be done?

Thanks and kind regards

Be it the provider of your choice, your problem is not your provider but establishing a PPP session over serial port to route IP instead of doing it via WiFi. The rest of the configuration is the same and you can follow whatever tutorial/demo/example you may find
You should search the forum, this has already been answered here not so long ago; for the same cell modem
IoT provider examples you may find at the documentation page, here

As long as you are able to connect to the internet with your modem, you’ll be able to connect to whatever cloud service.