Hi Ralph,
I verify step by step evrything you asked me to do and come to the same result I got when first I started to troubleshoot my system from the switchboard. All my trunks shoe Busy or Idle some time but not out of service.
When I press function from the switchboard-press trunk function-enter any number of trunk- then attendant access, after hearing the dial tone; when you dial 001 following with a USA number ,without the leading "9", the number rings.