You may find it helpful to remember that if you have an FXO port and connect an analog line into it, it is just as if you connect an off-the-shelf telephone into the line. The router on an FXO port is 'just an analog telephone'.

When you pick up your analog telephone at home, you do not know what number has called you. You know what your number is because you pay for it, but there is no way for someone else to come in your house and pick up the phone and know what number someone else has dialed or is trying to reach.

For this reason we use plar. Plar automatically calls one number, and the call can be directed from there. This is where a receptionist or auto-attendant come in.

So the short answer is - sorry, it's a limitation of the FXO/FXS design and relationship. In order to directly dial in you would need a BRI/PRI or another type of circuit.

-nick