12:00 am EDT might be unsuitable for MT time zone
When planning a call between Eastern Daylight Time and Mountain Time, you need to consider time difference between these time zones. EDT is 2 hours ahead of MT.
It is 12:00 am in EDT. This does not fall within the span of usual working time between 9:00 am and 4:00 pm in MT, but it still might be suitable to arrange a meeting, since it would be 10:00 pm in MT, which is between 7:00 am and 11:00 pm MT time.