FYI concerning the Telit Charlie:
To my pleasant surprise Telit responded within days to my requests and published a first version of a mkrnb like library:
They also react to a bug within one day: The SDU.cpp is not adapted for charlie · Issue #2 · telit/arduino-charlie · GitHub
Question: Can someone help him compile the bootloader for the charlie board to the desired size? (See the issue)
I proposed a Telit Charlie board with a full LTE 1 or 4 modem with I2S connected.