finally I've managed to find the time to disassemble my CradlePoint PHS300 to take pictures of the hardware. The pictures can be found here: www.mulliner.org/hardware/cradlepoint_phs300
The hardware seems to be build based on the ubicom IP3023. From what I can see after a quick check of the SoC spec. this thing does not run Linux. This is sad since I really hoped this would be the case.