No-Answer Exclusion Time
From PhonePower Knowledge Base
This field is visible only if Hunt on no-answer is set to True. User Agents who do not answer a ringing call will be "excluded" for a period of time defined by this timer. No further Hunt Group calls (from any Hunt Group of which this line is a member) will be offered to them during this time. This means that calls into the User Agents should not be delayed by repeated attempts to ring a member who is not answering. The member can be offered calls again after the time has elapsed.