Create an analog extension for the call box and cross connect it, then create a hunt group with an extension list containing the members you want to ring (lets call it 2009), then go to the analog extension and set House Phone to Yes and set the House Phone Day and Night to 2009 (or wherever you want it to call in Day/Night).
When you push the button on the callbox, it goes off hook and the phone system dials the extension in the House Phone Day or Night field depending on the system mode.
House phone is roughly equivalent to Ring-Down or Auto-Dial on Off-Hook, this is nice for fax extensions too, put an 8 in both the fields and you don't have to add an 8 to those 300 speed dials the customer programmed in the fax machine.