I would like to send an SMS to a registered mobile phone from the code running in STM32 board.
It looks as though with the SIM900 you can do this. Check out this discussion related to your topic.
SIM900 appears to be a chip rather than a dev module. Am I wrong?
Yes, the SIM900 itself is a chip, but there are modules that use the chip. I realize that I linked to just the chip, but more so just for reference.
Module 1
Module 2
Module 3
There are more than just those 3. They just provide a starting point
