While I do think this is completely overcomplicated and you should rather rebuild the source than fiddling on this level, I'll tell you how to do it anyways: AT%CPI=4 enables the TI Calypso proprietary call progress status. See http://git.freesmartphone.org/?p=framework.git;a=blob_plain;f=framework/subsystems/ogsmd/modems/ti_calypso/unsolicited.py;hb=HEAD for details on the format. Have fun, :M: