One more thing you might try is to connect your FXO port to FXS port using a telephone line (like the one coming with the package), then, open the PHONE and LINE status page, and see if you can read TipRingVoltage. This way, the line voltage is provided by OBi110 itself, and it should guarantee you FXO port sense a voltage around -45 V if the unit is not defective.
If you have a line splitter, you can also connect both a regular telephone and FXO port to your FXS port, then, make a call into your SP1/OBiTALK, your phone will ring, so does your LINE port. Open PHONE and LINE status page again, you should see the LINE port state becomes "ringing".
If both 2 steps go well, then, we can look ahead to see why UK BS 6312 does not work with the LINE port