SIMCOM

SIM900 Driver for KEIL MDK-Network (PPP interface for TCP/IP)

I choose to use LPC4337 and the Cortex-M4 core. No particular preference, only that it was on my desk at the time I chose to write this post. Also, I bought this developer board here. The network driver is documented at length by Keil/ARM here, in case you need to familiarize yourself with it before proceeding.

There are 15 commits up to this one that detail the steps on how code changed through the process.

SIM900 Dial-up Connection Setup

SIM900 Dial-up Connection Setup

SIMCOM's SIM900 is the most common GSM/GPRS modules in the maker/hobbyist community. It is of course not the best and the experience people have had with it varies. Most people use this for simple tasks like SMS sending and receiving making the experience people have had largely positive. The module is also cheap and readily available. Compared to building your own baseband module, you get some advantages:

a) Certification of by regulatory institutions like FCC, CE, etc. is already done.

b) The software stack is already done. The only thing you have to worry about is the command protocol otherwise known as AT command set. The software stack is very deep and complicated and there are very few resources you will find online for this kind of work.

The list goes on...

Worth noting is that these benefits apply to almost all GSM module and so does most of the post below.