Change asterisk voicemail settings based on a schedule?

I need to set up an asterisk voicemail inbox that: * Works normally during business hours. * After business hours, calls to this line go straight to voicemail after a special "we're not in right now" recording plays. I think it should be possible to set the recording using custom time zones, but I'm not sure that is the best way to do it. I also don't know how to control "rings before voicemail" based on a schedule. Is this possible?