Magnificent web site. Plenty of useful info here. I am sending it to a few buddies ans additionally sharing in delicious. And certainly, thanks to your effort!
Each of the Button fields corresponds to a number on the caller's phone keypad. In this example, we're using Button 1 for sales ("Press 1 for sales"). For the key that corresponds to your IVR announcement, from the dropdown select Time Switches, then New Time Switch. If you would like to always route to a queue, instead of a time switch, select Queues, then New Queue and skip to Queue Setup below.

Context does matter here. If the caller would reasonably expect you to answer the phone (such as if they were calling a store or other place of business), an apology for not being able to get to the phone makes the most sense.
Voicemail greetings for business have to be very clear, precise, and to the point. Businessmen tend to avoid frivolous talks, so it is important that you stick to the basics. On the other hand, you can be funny or a little less formal while recording a voicemail for your friends and family. However, remember to adhere to voicemail etiquette while recording these greetings. So, this is where I sign out. Leave a message, I mean a comment if you like my voicemail greeting suggestions!