We have BCM450 with IP1230 phones. Our ringing service is set to manual and works correctly when out of the office. I was recently asked to not let any calls on the main receptionist phone go to voice mail. So I Cleard Fwd No Answer and all internal calls do not go to voice mail. External calls will ring for a longer period of time, but then will roll over to our ringing service. The preference is for them to continue ringing in the office unless the ringing service is engaged.