If you would like to have your calls routed differently after business hours there are several options available.
The first step is to enable after hours routing and define the hours that your business is open.
In the case of company phone numbers you should go to the phone numbers and routing tab.
In the case of departments you should go to the Departments tab.
If you would like your calls to be handled differently for a period of time during a holiday the best way to do this is through an IVR (voice menu) tree. You will then be able to reuse this greeting and routing setup with little to no changes in the future. A detailed explanation can be found in the voice menu page.