State your name clearly so the caller knows they have the right number. 3 of the messages I heard last month were missing his/her name.
Hello. You have reached [Insert employee name here] in the [Insert department name here] office at UNI. I will be out of the office from [insert day of the week, month, date] through [insert day of the week, month, date]. Please leave a message and I will return your call on [insert day of the week, month, date]. If you require assistance prior to [month, date], hang up and dial our main departmental number at 273-[insert phone number here]. The main departmental voice mail will be checked daily on Dec. 28, 29, 30 and 31. Return calls will be made if an immediate response is needed.

Rehearse or write down your message before recording it. Remember that old saying “practice makes perfect?” It’s certainly true when it comes to creating an electronic greeting. The more you’ve rehearsed, the easier the message will be to restate. If you don’t have time to practice, writing down the greeting before recording it – and then reading it aloud from the paper – may help you stay focused on the correct wording.
You don’t have to spell out every single thing that you think they might want to know. Have some faith that your callers will be able to figure things out on their own. Be natural but informative.