said by martinburger:Thanks, I am now provisioned and pointing to Chicago. Everything seems to be working fine now. I had to change the "number of seconds your phone will ring before it goes to voicemail" to the smallest value offered, which was 5. If a call comes in and one is on the phone, the second line will ring, when the system wants to go to voicemal, it will then generate the busy signal. When set to 5 seconds, this results in the caller hearing one ring then the busy signal. I am fine with this, it even gives me the oportunity to see via caller id who the caller actually was.
Again many thanks for your help.
As an update, setting number of rings to 5 was incorrect, all calls went busy after one ring. I tested it by dialing my number with another phone and picking up after first ring and then tested the busy signal logic by then placing a call.
My current configuration works even better. I set number of rings to 30, more than enough time for my answering machine to pick up. I then disabled my second line via control panel. This resulted in an immediate busy signal to caller if I am on the line - PLUS - I still can make outgoing calls on the second line! The best of both worlds.