If the in-use trunk is out of service, a customer needs to ensure that outgoing...

by setting an Out of Service trunk on the primary trunk

by enabling the In Service option and add the primary ARS in the In Service Route on the secondary ARS

by setting the Time Profile with a business hours profile, and adding a secondary ARS in the Out of Hours Route on the primary ARS

by enabling the In Service option and add a secondary ARS in the Out of Service Route on the primary ARS