I've finally got it working --- CALL RECORDING - 2 WAY on HTC Evo 4G CRYSTAL CLEAR!
This is an old thread but FYI, you can have the HTC EVO 4G recording both sides, full clarity and in the background if you so choose. I worked on this for months and finally was able to get all the components together to install.. I don't know how much interest there is but if there is enough interest here I'll write a tutorial and provide the links to the files you'l need. It's not a difficult process but will require rooting, a rom update, a kernel replacment and the actual call recording software. So let me know if this is something with a high level of interest here and I'll get an instruction / tutorial written up. It will take me a little time to gather and verify the links, write the instructions, etc., but i'll be happy to if the interest is here.
This may work on some other Android roms running any of the new ICS android 4.0 roms but was not tested on alternatives.
