Setting up callback/disa

I want to have a setup so I can call my number, get a bust tone, get a call back and be presented with a dial tone so I can call out as if I am in the office.

How can I go about this?

Thanks for all your help in sorting all us noobs out!

Go here:
Scroll down to "One Ringy-Dingy"
I set this up back when I was using * 1.2 and it worked just fine.
The syntax may have changed slightly in * 1.4, but most of it should work as is.