Hi Marcin,
did you ever find schematics of the Sciphone G2 anywhere online? It would be great to understand which of the I/O lines are connected to which peripherals, especially for the GSM part.
Also, do you know the RF transceiver chip used in the device? We already know the MT6129 and MT6139 from the MT622x based phones, but it might be a different one for the MT6235.