Why do the inbound calls of a certain trunk would be hung up during a specific time period?
It is because that the system has enabled “Business hours” and the destination of “non office hour” has been configured to “End calls” in the inbound routes. Please follow the steps to change the settings:

Step 1: Figure out which is the trunk that has the problem and check all the inbound routes that use this trunk.
Step 2: Solve the problem by changing the destination of “Non-office hours” in the “Edit Inbound route” page.