Dial to IVR

Hello all,

I have 1 question. Currently i creating company IVR, reachable from PRI from telco. It’s not so complicated. Top menu and then 3 language selection under it. "If you know number please dial it, if not press 1 to connect to operator."
I have the following problem:
In case of customer calling through IVR to extension which is busy or unavailable, it’s getting busy and call disconnecting.I would like that the call under this condition will return back to IVR. And in addition, in case of operator is transferring the call to busy/unavailable/no one is answering, the call will return to operator. How i can accomplish this task???

Thanks in advance, Alex