I can say with certainty that the X100P and the soekris 4801 are not compatible. The soerkis will not power up with a X100P installed. I ended up using a sipura spa-3000 for FXO/FXS connectivity with asterisk. In this configuration asterisk runs great on the soekris. I wish someone would make a 3.3 volt single port FXO device to replace the X100p given that it is now discontinued anyways.