DISA (parallel actions?)

I am wondering whether this is possible:

  1. User dials my PSTN number
  2. Asterisk picks it up and immediately starts a ringing tone
  3. The default extension is ringing by this time - so anyone can pick it up
  4. While this is happening, the caller can press some keys and the default extension stops ringing and the caller is presented with the inside tone awaiting password.

In a nutshell, standard DISA, except that a phone is ringing somewhere while awaiting the DISA access number to be dialled.

Dial() with option d