This presentation covers some of our recent explorations into a specific type of 3G/4G cellular modems, which next to the regular modem/baseband processor also contain a Cortex-A5 core that (unexpectedly) runs Linux.
We want to use such modems for building self-contained M2M devices that run the entire application inside the modem itself, without any external needs except electrical power, SIM card and antenna.
Next to that, they also pose an ideal platform for testing the Osmocom network-side projects for running GSM, GPRS, EDGE, UMTS and HSPA cellular networks.
The results of our reverse engineering can be found in the wiki at http://osmocom.org/projects/quectel-modems/wiki together with links to the various git repositories containing related tools.
As with all the many projects that I happen to end up doing, it would be great to get more people contributing to them. If you're interested in cellular technology and want to help out, feel free to register at the osmocom.org site and start adding/updating/correcting information to the wiki.
You can e.g. help by
playing with the modem and documenting your findings
reviewing the source code released by Qualcomm + Quectel and documenting your findings
help us to create a working OE build with our own kernel and rootfs images as well as opkg package feeds for the modems
help reverse engineering DIAG and QMI protocols as well as the open source programs to interact with them