I guess I should have explain with more detail.

At the idle station 33, I want to make a intercom call to station to station 12, for this example.

I lift the handset and press the intercom button and I clearly get busy tone. It is not a restricted tone.
If station 12 calls station 33 , 33 rings and I can anser the intercom call.
The ASL is set for Outside lines, and I have no trouble answering calls or making call outside.

Thanks again