I just noticed some specs for the chip: "Cortex M4 1MB, 16 MHz, 32.768 KHz, Sleep Timer". Does that offer you any clues? They also say:
It works like an Ardunio and can run Wiring, Python, ARM assembly or whatever code you'd like to use. It's open source, and infinitely hackable, so you can easily adjust and build the Dash into any of your own projects
You're right about SIM900, but it's only 2G, which is already being phased out in the US and Australia, and possibly other regions to follow soon. So SIM900 isn't really an option for me, at least not if you're creating a product to be used in various countries.
(Makes you wonder how long 3G has left..)
Dash uses u-blox Sara which is 2G+3G, but it has variants for either Americas or Europe/Asia and I don't know which one it is (I just asked on Kickstarter). Dash Pro uses u-blox Lisa which is 3.75G and works just about all over the world. One thing is certain, the world of mobile networks is messy.