**8 on an OBi110, not an OBi10xx is used to route calls to line.
Below is a copy of my OBi1032's Phone DigitMap and OutboundCallRoute. **8 is used to route calls to Bluetooth and **70 is used to route calls to line. I think OBi support had one too many last night.
([1-9]x?*(Mpli)|[1-9]S9|[1-9][0-9]S9|***|**0|#|##|**70(Mli)|**8(Mbt)|**1(Msp1)|**2(Msp2)|**3(Msp3)|**4(Msp4)|**6(Msp6)|**9(Mpp)|(Mpli))
{([1-9]x?*(Mpli)):pp},{**0:aa},{***:aa2},{(<**1:>(Msp1)):sp1},{(<**2:>(Msp2)):sp2},{(<**3:>(Msp3)):sp3},{(<**4:>(Msp4)):sp4},{(<**6:>(Msp6)):sp6},{(<##:>):li},{(<**70:>(Mli)):li},{(<**8:>(Mbt)):bt},{(<**9:>(Mpp)):pp},{(Mpli):pli}