To achieve this you would need to add a rule at the beginning of the Phone 1 and Phone 2 OutboundCallRoutes like so:
Phone 1-->OutboundCallRoute
{911:bt},{([1-9]x?*(Mpli)):pp},{(<#:>):ph2},{(<**8:>(Mbt)):bt},{**0:aa},{***:aa2},{(<**1:>(Msp1)):sp1},{(<**2:>(Msp2)):sp2},{(<**3:>(Msp3)):sp3},{(<**4:>(Msp4)):sp4},{(<**9:>(Mpp)):pp},{(Mpli):pli}
If you live alone, then this works fine. If others live in the household, then this looks like a risky strategy as dialling 911 from a house phone will sometimes work and sometimes not.