Erlang doesnt meet every criteria especially if you go to extremes of occupancy or handle times.
Why do you only want your agents occupied for just 35% of the time ? Would it not make more sense to operate with fewer agents but with higher occupancy ? with your statement you are indicating that the agents are really only going to deal with 1 call an hour.
What are your agents doing for the other 65% of the hour, say in available waiting for a call to come in ?
If other calls are taken by this team, you need to amalgamate the workload rather than looking at each part in isolation