in Telephony

hacking the Samsung a920 mobile phone

I spent part of the weekend hacking my company-issued Samsung a920 cell phone. I guess “hacking” is a bit of a strong term – my sole objective was to get certain MIDP applications installed on it. I have a nameless-but-trustworthy-source inside Bell Mobility that confirms they block the download of MIDP apps that it doesn’t like, for example, MidpSSH or Opera Mini. Presumably, they do this by parsing the JAD file and rejecting source domains in the MIDlet-Jar-URLthat aren’t in a whitelist.

Fortunately, this thread on HowardForums gives you the lowdown on how to break into the a920 firmware to forcibly load MIDP applications on there. I had to really screw around with UniCDMA (i.e. randomly selecting different phone models) before it would spit out my SPC, but eventually I got it. The instructions on using Qualcomm’s EFS Explorer worked like a charm.

I have to admire the phone developers for their humour in naming various directories on the phone’s filesystem. The root is called "brew", presumably because the phone is Java-capable. The _policy.txt file that you can overwrite in order to remove some of the restrictions on the phone lives in a directory called "obione". (I didn’t touch the _policy.txt because I accomplished my goal just by writing the apps to the phone’s filesystem, which is good enough for me.)

Anyway, I now have Opera Mini and MidpSSH running nicely on the phone! (Nicely, I guess, if you consider that typing SSH commands using T9 is pretty painful.)